Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense Helium
Militzer, Burkhard
Path Integral Monte Carlo and Density Functional Molecular Dynamics Simulations of Hot, Dense integral Monte Carlo (PIMC) and density func- tional molecular dynamics (DFT-MD), are applied to study hot excitation mecha- nisms that determine their behavior at high temperature. The helium atom has two ionization
PuReMD-GPU: A reactive molecular dynamics simulation package for GPUs
Kylasa, S.B., E-mail: skylasa@purdue.edu [Department of Elec. and Comp. Eng., Purdue University, West Lafayette, IN 47907 (United States); Aktulga, H.M., E-mail: hmaktulga@lbl.gov [Lawrence Berkeley National Laboratory, 1 Cyclotron Rd, MS 50F-1650, Berkeley, CA 94720 (United States); Grama, A.Y., E-mail: ayg@cs.purdue.edu [Department of Computer Science, Purdue University, West Lafayette, IN 47907 (United States)
2014-09-01T23:59:59.000Z
We present an efficient and highly accurate GP-GPU implementation of our community code, PuReMD, for reactive molecular dynamics simulations using the ReaxFF force field. PuReMD and its incorporation into LAMMPS (Reax/C) is used by a large number of research groups worldwide for simulating diverse systems ranging from biomembranes to explosives (RDX) at atomistic level of detail. The sub-femtosecond time-steps associated with ReaxFF strongly motivate significant improvements to per-timestep simulation time through effective use of GPUs. This paper presents, in detail, the design and implementation of PuReMD-GPU, which enables ReaxFF simulations on GPUs, as well as various performance optimization techniques we developed to obtain high performance on state-of-the-art hardware. Comprehensive experiments on model systems (bulk water and amorphous silica) are presented to quantify the performance improvements achieved by PuReMD-GPU and to verify its accuracy. In particular, our experiments show up to 16× improvement in runtime compared to our highly optimized CPU-only single-core ReaxFF implementation. PuReMD-GPU is a unique production code, and is currently available on request from the authors.
Molecular dynamics (MD) calculation of the real zeta potential of neutral surfaces
Liu, Hongyi
2013-01-01T23:59:59.000Z
Molecular dynamics (MD) simulations of the zeta potential are so poor that it has become common to term their predictions "apparent". Here we demonstrate how MD methods can predict zeta potentials accurate enough they can be termed "real". The critical new aspects of our method are: (1) integrating the net average charge in surface-parallel layers from the midpoint of the fluid layer (where the electrostatic potential is zero) to and then into two solid caps, (2) determining the position of slipping plane with separate Couette flow models, and (3) calculating the charge distribution and electrostatic potential under static conditions. The solids are charge neutral surfaces composed of atoms with zero charge or charge balanced monovalent or divalent ions. The zeta potentials calculated are within a few millivolts of measured values, and the measured values fall within the simulation error bars. The zeta potentials calculated with the Helmholtz and Smoluchowski equation following current practice are 10's of mi...
Fast plane wave density functional theory molecular dynamics calculations on multi-GPU machines
Jia, Weile, E-mail: jiawl@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China) [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing (China); Fu, Jiyun, E-mail: fujy@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China) [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); University of Chinese Academy of Sciences, Beijing (China); Cao, Zongyan, E-mail: zycao@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China)] [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); Wang, Long, E-mail: wangl@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China)] [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); Chi, Xuebin, E-mail: chi@sccas.cn [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China)] [Supercomputing Center, Computer Network Information Center, Chinese Academy of Sciences, No. 4 South 4th Street, ZhongGuanCun, Beijing 100190 (China); Gao, Weiguo, E-mail: wggao@fudan.edu.cn [School of Mathematical Sciences, Fudan University, 220 Handan Road, Shanghai 200433 (China) [School of Mathematical Sciences, Fudan University, 220 Handan Road, Shanghai 200433 (China); MOE Key Laboratory of Computational Physical Sciences, Fudan University, Shanghai (China); Wang, Lin-Wang, E-mail: lwwang@lbl.gov [Material Science Division, Lawrence Berkeley National Laboratory, One Cyclotron Road Mail Stop 50F Berkeley, CA 94720 (United States)] [Material Science Division, Lawrence Berkeley National Laboratory, One Cyclotron Road Mail Stop 50F Berkeley, CA 94720 (United States)
2013-10-15T23:59:59.000Z
Plane wave pseudopotential (PWP) density functional theory (DFT) calculation is the most widely used method for material simulations, but its absolute speed stagnated due to the inability to use large scale CPU based computers. By a drastic redesign of the algorithm, and moving all the major computation parts into GPU, we have reached a speed of 12 s per molecular dynamics (MD) step for a 512 atom system using 256 GPU cards. This is about 20 times faster than the CPU version of the code regardless of the number of CPU cores used. Our tests and analysis on different GPU platforms and configurations shed lights on the optimal GPU deployments for PWP-DFT calculations. An 1800 step MD simulation is used to study the liquid phase properties of GaInP.
Oberhofer, Harald; Blumberger, Jochen [Department of Chemistry, University of Cambridge, Cambridge CB2 1EW (United Kingdom)
2009-08-14T23:59:59.000Z
We present a plane-wave basis set implementation of charge constrained density functional molecular dynamics (CDFT-MD) for simulation of electron transfer reactions in condensed phase systems. Following the earlier work of Wu and Van Voorhis [Phys. Rev. A 72, 024502 (2005)], the density functional is minimized under the constraint that the charge difference between donor and acceptor is equal to a given value. The classical ion dynamics is propagated on the Born-Oppenheimer surface of the charge constrained state. We investigate the dependence of the constrained energy and of the energy gap on the definition of the charge and present expressions for the constraint forces. The method is applied to the Ru{sup 2+}-Ru{sup 3+} electron self-exchange reaction in aqueous solution. Sampling the vertical energy gap along CDFT-MD trajectories and correcting for finite size effects, a reorganization free energy of 1.6 eV is obtained. This is 0.1-0.2 eV lower than a previous estimate based on a continuum model for solvation. The smaller value for the reorganization free energy can be explained by the fact that the Ru-O distances of the divalent and trivalent Ru hexahydrates are predicted to be more similar in the electron transfer complex than for the separated aqua ions.
Chen, Sow-Hsin
2010-01-01T23:59:59.000Z
This review article describes our neutron scattering experiments made in the past four years for the understanding of the single-particle (hydrogen atom) dynamics of a protein and its hydration water and the strong coupling ...
Dynamical density functional theory for colloidal particles with arbitrary shape
Raphael Wittkowski; Hartmut Löwen
2011-06-12T23:59:59.000Z
Starting from the many-particle Smoluchowski equation, we derive dynamical density functional theory for Brownian particles with an arbitrary shape. Both passive and active (self-propelled) particles are considered. The resulting theory constitutes a microscopic framework to explore the collective dynamical behavior of biaxial particles in nonequilibrium. For spherical and uniaxial particles, earlier derived dynamical density functional theories are recovered as special cases. Our study is motivated by recent experimental progress in preparing colloidal particles with many different biaxial shapes.
Dynamics of localized particles from density functional theory
Johannes Reinhardt; Joseph Michael Brader
2011-11-23T23:59:59.000Z
A fundamental assumption of the dynamical density functional theory (DDFT) of colloidal systems is that a grand-canonical free energy functional may be employed to generate the thermodynamic driving forces. Using one-dimensional hard-rods as a model system we analyze the validity of this key assumption and show that unphysical self-interactions of the tagged particle density fields, arising from coupling to a particle reservoir, are responsible for the excessively fast relaxation predicted by the theory. Moreover, our findings suggest that even employing a canonical functional would not lead to an improvement for many-particle systems, if only the total density is considered. We present several possible schemes to suppress these effects by incorporating tagged densities. When applied to confined systems we demonstrate, using a simple example, that DDFT neccessarily leads to delocalized tagged particle density distributions, which do not respect the fundamental geometrical contraints apparent in Brownian dynamics simulation data. The implication of these results for possible applications of DDFT to treat the glass transition are discussed.
Hybrid Dynamic Density Functional Theory for Polymer Melts and Blends
Takashi Honda; Toshihiro Kawakatsu
2006-09-05T23:59:59.000Z
We propose a high-speed and accurate hybrid dynamic density functional theory for the computer simulations of the phase separation processes of polymer melts and blends. The proposed theory is a combination of the dynamic self-consistent field (SCF) theory and a time-dependent Ginzburg-Landau type theory with the random phase approximation (GRPA). The SCF theory is known to be accurate in evaluating the free energy of the polymer systems in both weak and strong segregation regions although it has a disadvantage of the requirement of a considerable amount of computational cost. On the other hand, the GRPA theory has an advantage of much smaller amount of required computational cost than the SCF theory while its applicability is limited to the weak segregation region. To make the accuracy of the SCF theory and the high-performance of the GRPA theory compatible, we adjust the chemical potential of the GRPA theory by using the SCF theory every constant time steps in the dynamic simulations. The performance of the GRPA and the hybrid theories is tested by using several systems composed of an A/B homopolymer, an AB diblock copolymer, or an ABC triblock copolymer. Using the hybrid theory, we succeeded in reproducing the metastable complex phase-separated domain structures of an ABC triblock copolymer observed by experiments.
Harvesting graphics power for MD simulations
J. A. van Meel; A. Arnold; D. Frenkel; S. F. Portegies Zwart; R. G. Belleman
2007-09-20T23:59:59.000Z
We discuss an implementation of molecular dynamics (MD) simulations on a graphic processing unit (GPU) in the NVIDIA CUDA language. We tested our code on a modern GPU, the NVIDIA GeForce 8800 GTX. Results for two MD algorithms suitable for short-ranged and long-ranged interactions, and a congruential shift random number generator are presented. The performance of the GPU's is compared to their main processor counterpart. We achieve speedups of up to 80, 40 and 150 fold, respectively. With newest generation of GPU's one can run standard MD simulations at 10^7 flops/$.
Dynamical density functional theory with hydrodynamic interactions and colloids in unstable traps
M. Rex; H. Loewen
2008-03-13T23:59:59.000Z
A density functional theory for colloidal dynamics is presented which includes hydrodynamic interactions between the colloidal particles. The theory is applied to the dynamics of colloidal particles in an optical trap which switches periodically in time from a stable to unstable confining potential. In the absence of hydrodynamic interactions, the resulting density breathing mode, exhibits huge oscillations in the trap center which are almost completely damped by hydrodynamic interactions. The predicted dynamical density fields are in good agreement with Brownian dynamics computer simulations.
Last Name First Name Degree Abookire Susan MD, MPH
Paulsson, Johan
Frey-Vogel Ariel MD, MAT Garfield Joseph M.D. Gaufberg Elizabeth MD MPH Ghosh Arundhati MBBS, FRCS MD Miller Katherine MD Minehart Rebecca M.D. Mitchell John MD Monaghan Colleen MD Muto Michael MD-Vernaglia Shannon MD Shapiro Jo MD Sharma Niraj MD, MPH Sharp John MD Shields Helen MD Ship Amy MD Simone
Dynamics of disentanglement, density matrix, and coherence in neutrino oscillations
Wu Jun; Boyanovsky, Daniel [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Hutasoit, Jimmy A.; Holman, Richard [Department of Physics, Carnegie Mellon University, Pittsburgh, Pennsylvania 15213 (United States)
2010-07-01T23:59:59.000Z
In charged current weak interaction processes, neutrinos are produced in an entangled state with the charged lepton. This correlated state is disentangled by the measurement of the charged lepton in a detector at the production site. We study the dynamical aspects of disentanglement, propagation, and detection, in particular, the conditions under which the disentangled state is a coherent superposition of mass eigenstates. The appearance and disappearance far-detection processes are described from the time evolution of this disentangled 'collapsed' state. The familiar quantum mechanical interpretation and factorization of the detection rate emerges when the quantum state is disentangled on time scales much shorter than the inverse oscillation frequency, in which case the final detection rate factorizes in terms of the usual quantum mechanical transition probability provided the final density of states is insensitive to the neutrino energy difference. We suggest possible corrections for short-baseline experiments. If the charged lepton is unobserved, neutrino oscillations and coherence are described in terms of a reduced density matrix obtained by tracing out an unobserved charged lepton. The diagonal elements in the mass basis describe the production of mass eigenstates whereas the off-diagonal ones provide a measure of coherence. It is shown that coherences are of the same order of the diagonal terms on time scales up to the inverse oscillation frequency, beyond which the coherences oscillate as a result of the interference between mass eigenstates.
Correll, S.
1988-04-01T23:59:59.000Z
MD is the S-1 Mark IIA machine debugger. It is the hardware equivalent of a software symbolic debugger. It consists of a user-level program which executes on a VAX computer running Berkeley UNIX and a device driver which resides within the UNIX kernel. It communicates with the S-1 Mark IIA through a front-end interface attached to the UNIBUS of the VAX. The first section of this report describes MD's user interface and command set. The second section describes the virtual machine interface through which MD and the UNIX device driver communicate.
SciTech Connect: Chiral dynamics and peripheral transverse densities
Office of Scientific and Technical Information (OSTI)
in terms of frame-independent charge and magnetization densities in transverse space. This formulation allows one to identify the chiral components of nucleon structure as...
Benjamin D. Goddard; Andreas Nold; Nikos Savva; Grigorios A. Pavliotis; Serafim Kalliadasis
2012-08-08T23:59:59.000Z
We study the dynamics of a colloidal fluid including inertia and hydrodynamic interactions, two effects which strongly influence the non-equilibrium properties of the system. We derive a general dynamical density functional theory (DDFT) which shows very good agreement with full Langevin dynamics. In suitable limits, we recover existing DDFTs and a Navier-Stokes-like equation with additional non-local terms.
Why are MD simulated protein folding times wrong? Dmitry Nerukh
Nerukh, Dmitry
Why are MD simulated protein folding times wrong? Dmitry Nerukh Unilever Centre for Molecular.ac.uk The question of significant deviations of protein folding times simulated using molecular dynamics from
Light-front representation of chiral dynamics in peripheral transverse densities
Granados, C
2015-01-01T23:59:59.000Z
The nucleon's electromagnetic form factors are expressed in terms of the transverse densities of charge and magnetization at fixed light-front time. At peripheral transverse distances $b = O(M_\\pi^{-1})$ the densities are governed by chiral dynamics and can be calculated model-independently using chiral effective field theory (EFT). We represent the leading-order chiral EFT results for the peripheral transverse densities as overlap integrals of chiral light-front wave functions, describing the transition of the initial nucleon to soft pion-nucleon intermediate states and back. The new representation (a) explains the parametric order of the peripheral transverse densities; (b) establishes an inequality between the spin-independent and -dependent densities; (c) exposes the role of pion orbital angular momentum in chiral dynamics; (d) reveals a large left-right asymmetry of the current in a transversely polarized nucleon and suggests a simple interpretation. The light-front representation enables a first-quantiz...
Distributed delay model for density wave dynamics in gas lifted wells Laure Sin`egre, Nicolas Petit
Distributed delay model for density wave dynamics in gas lifted wells Laure Sin`egre, Nicolas Petit in the tubing D. dynamical choking is used to stabilise the density wave instability. In this paper, we propose instabilities cause production losses. One of these instabilities, referred to as the "density-wave
Dynamical friction in constant density cores: a failure of the Chandrasekhar formula
J. I. Read; Tobias Goerdt; Ben Moore; A. P. Pontzen; Joachim Stadel; George Lake
2006-06-26T23:59:59.000Z
Using analytic calculations and N-body simulations we show that in constant density (harmonic) cores, sinking satellites undergo an initial phase of very rapid (super-Chandrasekhar) dynamical friction, after which they experience no dynamical friction at all. For density profiles with a central power law profile of log-slope, $-\\alpha$, the infalling satellite heats the background and causes $\\alpha$ to decrease. For $\\alpha < 0.5$ initially, the satellite generates a small central constant density core and stalls as in the $\\alpha = 0$ case. We discuss some astrophysical applications of our results to decaying satellite orbits, galactic bars and mergers of supermassive black hole binaries. In a companion paper we show that a central constant density core can provide a natural solution to the timing problem for Fornax's globular clusters.
Susan P. Taylor, MD Shorewood, Wisconsin
Noxapater, Mississippi Corey W. Gilliland, MD Mesa, Arizona Jeanne V. Hamel, MD Elk Grove, California Steven Manhattan, Kansas Dean Afif Shoucair, DO Frankfort, Illinois John Mitchell Simson, MD Albuquerque, New
Liquids that form due to dynamics of the molecules that depend on the local density
Richard P. Sear
2015-03-26T23:59:59.000Z
RNA molecules in living cells form what look like liquid droplets formed by liquid/liquid phase separation. But unlike the molecules in conventional phase separating mixtures, RNA molecules are transported by molecular motors that consume energy and so are out of equilibrium. Motivated by this we consider what sort of simple rules for the dynamics of model mRNA molecules lead to liquid/liquid phase separation. We find that dynamics that slow as the local density of molecules increases, drive the formation of liquids. We also look at the analogous separation of the two blocks of a block copolymer, in which the monomers of one block have dynamics that depend on the local density of monomers of that block. We find that this block condenses and separates from the monomers of the other block. This is a simple model of the out-of-equilibrium domain formation found in the chromatin in the nucleus of cells.
Hammer, David
Where to find the mind: Identifying the scale of cognitive dynamics Luke Conlin, Department as occurring within individual minds and those that treat it as irreducibly distributed or situated in material and social contexts. We contend that accounts of individual minds as complex systems are theoretically
Two-flavor condensates in chiral dynamics: temperature and isospin density effects
M. Loewe; C. Villavicencio
2005-05-17T23:59:59.000Z
Isospin density and thermal corrections for several condensates are discussed, at the one-loop level, in the frame of chiral dynamics with pionic degrees of freedom. The evolution of such objects give an additional insight into the condensed-pion phase transition, that occurs basically when $|\\mui|>m_\\pi$, being $|\\mui|$ the isospin chemical potential. Calculations are done in both phases, showing a good agreement with lattice results for such condensates.
Dynamical density functional theory for the diffusion of injected Brownian particles
H. Löwen; M. Heinen
2014-09-08T23:59:59.000Z
While the theory of diffusion of a single Brownian particle in confined geometries is well-established by now, we discuss here the theoretical framework necessary to generalize the theory of diffusion to dense suspensions of strongly interacting Brownian particles. Dynamical density functional theory (DDFT) for classical Brownian particles represents an ideal tool for this purpose. After outlining the basic ingredients to DDFT we show that it can be readily applied to flowing suspensions with time-dependent particle sources. Particle interactions lead to considerable layering in the mean density profiles, a feature that is absent in the trivial case of noninteracting, freely diffusing particles. If the particle injection rate varies periodically in time with a suitable frequency, a resonance in the layering of the mean particle density profile is predicted.
Dynamic density field measurements of an explosively driven ????? phase transition in iron
Hull, L. M.; Gray, G. T.; Warthen, B. J. [Los Alamos National Laboratory, Los Alamos, New Mexico 87544 (United States)
2014-07-28T23:59:59.000Z
We provide a unique set of observations of the behavior of the ??? phase transition under a complex axially symmetric loading path created by sweeping a detonation wave along the end surface of a cylindrical sample. The primary data sets are the measured mass density distributions acquired at 5 independent times during the sweep of the detonation along the surface. Shocked regions and boundaries are measured, as well as regions and boundaries of elevated density (presumed to be the ??phase iron). The formation and dynamics of these regions were captured and are available for comparisons to material descriptions. We also applied 16 Photon Doppler Velocimetry probes to capture the free surface velocity along a discrete set of radially distributed points in order to compare and correlate the density measurements with previous shock wave studies. The velocimetry data are in nearly exact agreement with previous shock wave studies of the ??? phase transition, the density distributions, while generally in agreement with expectations evolved from the shock wave studies, show that the epsilon phase is generated in regions of high shear stress but at hydrostatic stresses below the typically quoted 13?GPa value. The density field measurements are particularly useful for observing the effects of the forward and reverse transformation kinetics, as well as the reverse transformation hysteresis.
Takashi Nakatsukasa
2012-10-01T23:59:59.000Z
We present the basic concepts and our recent developments in the density functional approaches with the Skyrme functionals for describing nuclear dynamics at low energy. The time-dependent density-functional theory (TDDFT) is utilized for the exact linear response with an external perturbation. For description of collective dynamics beyond the perturbative regime, we present a theory of a decoupled collective submanifold to describe for a slow motion based on the TDDFT. Selected applications are shown to demonstrate the quality of their performance and feasibility. Advantages and disadvantages in the numerical aspects are also discussed.
Fluorescence of PRODAN in Water: a Computational QM/MM MD Study
Pederzoli, Marek; Sobek, Lukas; Brabec, Jiri; Kowalski, Karol; Cwiklik, Lukasz; Pittner, Jiri
2014-03-28T23:59:59.000Z
Fluorescent properties of PRODAN (6-propionyl-2-dimethylaminonaphthalene) in water were studied by means of excited state molecular dynamics simulations employing a combined quantum mechanical and molecular mechanical approach with the time-dependent density functional theory (TD-DFT QM/MM MD). The state of the art coupled cluster method was used to benchmark density functional theory calculations. The influence of the water environment on PRODAN emission was investigated by employing several computational schemes with varying description of the solvent. The issue of the molecular geometry of the excited state PRODAN molecule in water was addressed. The experimental emission spectrum was reproduced for the planar excited state conformer of PRODAN in the extended environment of 300 explicit water molecules. The planar conformer was shown to be predominantly responsible for fluorescence. The twisted isomer is strongly stabilized in water, but rapidly evolve towards a conical intersection, and hence the twisted conformer is fluorescently inactive.
Sven van Teeffelen; Cristian Vasile Achim; Hartmut Löwen
2013-02-05T23:59:59.000Z
A two-dimensional crystal of repulsive dipolar particles is studied in the vicinity of its melting transition by using Brownian dynamics computer simulation, dynamical density functional theory and phase-field crystal modelling. A vacancy is created by taking out a particle from an equilibrated crystal and the relaxation dynamics of the vacancy is followed by monitoring the time-dependent one-particle density. We find that the vacancy is quickly filled up by diffusive hopping of neighbouring particles towards the vacancy center. We examine the temperature dependence of the diffusion constant and find that it decreases with decreasing temperature in the simulations. This trend is reproduced by the dynamical density functional theory. Conversely, the phase field crystal calculations predict the opposite trend. Therefore, the phase-field model needs a temperature-dependent expression for the mobility to predict trends correctly.
Dynamic density functional theory of protein adsorption on polymer-coated nanoparticles
Stefano Angioletti-Uberti; Matthias Ballauff; Joachim Dzubiella
2014-07-30T23:59:59.000Z
We present a theoretical model for the description of the adsorption kinetics of globular proteins onto charged core-shell microgel particles based on Dynamic Density Functional Theory (DDFT). This model builds on a previous description of protein adsorption thermodynamics [Yigit \\textit{et al}, Langmuir 28 (2012)], shown to well interpret the available calorimetric experimental data of binding isotherms. In practice, a spatially-dependent free-energy functional including the same physical interactions is built, and used to study the kinetics via a generalised diffusion equation. To test this model, we apply it to the case study of Lysozyme adsorption on PNIPAM coated nanoparticles, and show that the dynamics obtained within DDFT is consistent with that extrapolated from experiments. We also perform a systematic study of the effect of various parameters in our model, and investigate the loading dynamics as a function of proteins' valence and hydrophobic adsorption energy, as well as their concentration and that of the nanoparticles. Although we concentrated here on the case of adsorption for a single protein type, the model's generality allows to study multi-component system, providing a reliable instrument for future studies of competitive and cooperative adsorption effects often encountered in protein adsorption experiments.
Mass-density and Phonon-frequency Relaxation Dynamics of Water and Ice at Cooling
Chang Q. Sun
2013-04-02T23:59:59.000Z
Coulomb repulsion between the bonding electron pair in the H-O covalent bond (denoted by "-") and the nonbonding electron pair of O (":") and the specific-heat disparity between the O:H and the H-O segments of the entire hydrogen bond (O:H-O) are shown to determine the O:H-O bond angle-length-stiffness relaxation dynamics and the density anomalies of water and ice. The bonding part with relatively lower specific-heat is more easily activated by cooling, which serves as the "master" and contracts, while forcing the "slave" with higher specific-heat to elongate (via Coulomb repulsion) by different amounts. In the liquid and solid phases, the O:H van der Waals bond serves as the master and becomes significantly shorter and stiffer while the H-O bond becomes slightly longer and softer (phonon frequency is a measure of bond stiffness), resulting in an O:H-O cooling contraction and the seemingly "regular" process of cooling densification. In the water-ice transition phase, the master and the slave swap roles, thus resulting in an O:H-O elongation and volume expansion during freezing. In ice, the O--O distance is longer than it is in water, resulting in a lower density, so that ice floats.
Nomura, K.; Vretenar, D. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Niksic, T. [Physics Department, Faculty of Science, University of Zagreb, 10000 Zagreb (Croatia); Otsuka, T. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Center for Nuclear Study, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824-1321 (United States); Shimizu, N. [Department of Physics, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan); Center for Nuclear Study, University of Tokyo, Hongo, Bunkyo-ku, Tokyo 113-0033 (Japan)
2011-07-15T23:59:59.000Z
Microscopic energy density functionals have become a standard tool for nuclear structure calculations, providing an accurate global description of nuclear ground states and collective excitations. For spectroscopic applications, this framework has to be extended to account for collective correlations related to restoration of symmetries broken by the static mean field, and for fluctuations of collective variables. In this paper, we compare two approaches to five-dimensional quadrupole dynamics: the collective Hamiltonian for quadrupole vibrations and rotations and the interacting boson model (IBM). The two models are compared in a study of the evolution of nonaxial shapes in Pt isotopes. Starting from the binding energy surfaces of {sup 192,194,196}Pt, calculated with a microscopic energy density functional, we analyze the resulting low-energy collective spectra obtained from the collective Hamiltonian, and the corresponding IBM Hamiltonian. The calculated excitation spectra and transition probabilities for the ground-state bands and the {gamma}-vibration bands are compared to the corresponding sequences of experimental states.
Mootha, Vamsi K.
Andrea Reilly, MD Milton Pediatric Associates - MGH 10 Hawthorne Place, Suite 110, MA 02114 JonathanCullough, MD Rebecca Niloff, MD Cara O'Reilly, MD Scott Paul, MD Jonathon Brenner, MD John Robinson, MD Heidi-643-8120 Elizabeth Turnock, MD Pediatric Group Practice 55 Fruit Street, YAW 6D, MA 02114 Ronald Benz, MD 617
On the AU Mic debris disk: density profiles, grain properties and dust dynamics
J. C. Augereau; H. Beust
2006-04-13T23:59:59.000Z
We present the first comprehensive analysis of the AU Mic debris disk properties since the system was discovered by Kalas et al. (2004), and we explore whether the dynamical model, successful to reproduce the Beta Pic brightness profile could apply to AU Mic. We calculate the surface density profile of the AU Mic disk by performing the inversion of the near-IR and visible scattered light brightness profiles measured by Liu (2004a) and Krist et al. (2005), respectively. We discuss the grain properties by analysing the blue color of the disk in the visible (Krist et al. 2005) and by fitting the disk spectral energy distribution. We show that irrespective of the mean scattering asymmetry factor of the grains, most of the emission arises from an asymmetric, collisionally-dominated region that peaks close to the surface brightness break around 35 AU. The elementary scatterers at visible wavelengths are found to be sub-micronic, but the inferred size distribution underestimates the amount of large grains, resulting in too low sub-millimeter emissions compared to the observations. From our inversion procedure, we find that the V- to H-band scattering cross sections ratio increases outside 40 AU, in line with the observed color gradient of the disk. We show that a standard, solar-like stellar wind generates a pressure force onto the dust particles that behaves much like a radiation pressure force. With an assumed Mdot ~ 300 Mdot_sun, the wind pressure overcomes the radiation pressure and this effect is enhanced by the stellar flares. This explains the similarity between the Beta Pic and AU Mic brightness profiles. In both cases, the color gradient beyond 120 AU for Beta Pic and 35 AU for AU Mic, is believed to be a direct consequence of the dust dynamics.
Southern California, University of
Interaction potential for silicon carbide: A molecular dynamics study of elastic constants and vibrational density of states for crystalline and amorphous silicon carbide Priya Vashishta,a Rajiv K. Kalia Silicon carbide SiC has been proposed for a wide range of technological applications
Liu, Hao; Zhu, Lili; Bai, Shuming; Shi, Qiang, E-mail: qshi@iccas.ac.cn [Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190 (China)] [Beijing National Laboratory for Molecular Sciences, State Key Laboratory for Structural Chemistry of Unstable and Stable Species, Institute of Chemistry, Chinese Academy of Sciences, Zhongguancun, Beijing 100190 (China)
2014-04-07T23:59:59.000Z
We investigated applications of the hierarchical equation of motion (HEOM) method to perform high order perturbation calculations of reduced quantum dynamics for a harmonic bath with arbitrary spectral densities. Three different schemes are used to decompose the bath spectral density into analytical forms that are suitable to the HEOM treatment: (1) The multiple Lorentzian mode model that can be obtained by numerically fitting the model spectral density. (2) The combined Debye and oscillatory Debye modes model that can be constructed by fitting the corresponding classical bath correlation function. (3) A new method that uses undamped harmonic oscillator modes explicitly in the HEOM formalism. Methods to extract system-bath correlations were investigated for the above bath decomposition schemes. We also show that HEOM in the undamped harmonic oscillator modes can give detailed information on the partial Wigner transform of the total density operator. Theoretical analysis and numerical simulations of the spin-Boson dynamics and the absorption line shape of molecular dimers show that the HEOM formalism for high order perturbations can serve as an important tool in studying the quantum dissipative dynamics in the intermediate coupling regime.
Near quantitative agreement of model free DFT- MD predictions...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Near quantitative agreement of model free DFT- MD predictions with XAFS observations of the hydration structure of highly Near quantitative agreement of model free DFT- MD...
Editorial John Hickner, MD, MSc Editor-in-Chief
Alford, Simon
Health Care, Overland Park, Kan kEVin PEtErSon, MD, MPH University of Minnesota, St. Paul goutHAM rAo, MD
Richard P. Sear
2015-03-24T23:59:59.000Z
RNA molecules in living cells form what look like liquid droplets formed by liquid/liquid phase separation. But unlike the molecules in conventional phase separating mixtures, RNA molecules are transported by molecular motors that consume energy and so are out of equilibrium. Motivated by this we study models with out-of-equilibrium dynamics that depend on the local density. Our simulations suggest that density-dependent dynamics in which the motion of a molecule slows down in the presence of nearby molecules, tend to cause condensation into an out-of-equilibrium liquid state. This out-of-equilibrium state behaves like a liquid in the sense that it coexists with a much more dilute phase, droplets coalesce, and the state has a well-defined surface tension --- which we calculate. Liquid/liquid separation appears to be a very general phenomenon that occurs in and out of equilibrium. We also look at the analogous separation of the two blocks of a block copolymer, in which the monomers of one block have dynamics that depend on the local density of monomers of that block. We find that this block condenses and separates from the monomers of the other block. This is a simple model of the out-of-equilibrium domain formation found in the chromatin in the nucleus of cells.
E-Print Network 3.0 - applying dynamic flow-density Sample Search...
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Collection: Energy Storage, Conversion and Utilization 17 Dynamic Origin-Destination Demand Flow Estimation under Congested Traffic Conditions Xuesong Zhou Summary: for the...
DOCTOR'S HEART George Stetten, M.D.
Stetten, George
1 DOCTOR'S HEART George Stetten, M.D. "Resident Forum," Journal of the American Medical Association War --- soldier's heart. We should not be surprised or ashamed to find such reactions in ourselves
David Brick, MD, FAAP, FACC Image credit
#12;David Brick, MD, FAAP, FACC #12;Image credit: www.imagewisely.org #12;1) Understand why Adolescent medicine 12-24 years Brain scans show unique features. Adult congenital Brand new natural
Lessons Learned Tracy Glauser, M.D.
Lessons Learned Tracy Glauser, M.D. Cincinnati Children's Hospital Medical Center #12;Overview 1. Lessons Learned a. NeuroNEXT Executive Committee b. NINDS clinical trials (NSD-K) study section c. PI
Sear, Richard P
2015-01-01T23:59:59.000Z
RNA molecules in living cells form what look like liquid droplets formed by liquid/liquid phase separation. But unlike the molecules in conventional phase separating mixtures, RNA molecules are transported by molecular motors that consume energy and so are out of equilibrium. Motivated by this we study models with out-of-equilibrium dynamics that depend on the local density. Our simulations suggest that density-dependent dynamics in which the motion of a molecule slows down in the presence of nearby molecules, tend to cause condensation into an out-of-equilibrium liquid state. This out-of-equilibrium state behaves like a liquid in the sense that it coexists with a much more dilute phase, droplets coalesce, and the state has a well-defined surface tension --- which we calculate. Liquid/liquid separation appears to be a very general phenomenon that occurs in and out of equilibrium. We also look at the analogous separation of the two blocks of a block copolymer, in which the monomers of one block have dynamics t...
E-Print Network 3.0 - allen byrnes md Sample Search Results
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, M.D., 1975 Sue K. Anderson, M.D., 1977 Terry Allen Boulware, M.D., 1977 William E. Stricker, M.D... BAMD program. We also accept students into MD-only and MDoral surgery...
Rowland, Joel C [Los Alamos National Laboratory; Hilley, George E [STANFORD UNIV; Fildani, Andrea [CHEVRON ETC
2009-01-01T23:59:59.000Z
Leveed submarine channels play a critical role in the transfer of sediment from the upper continental slopes to interslope basins and ultimately deepwater settings. Despite a reasonable understanding of how these channels grow once established, how such channels initiate on previously unchannelized portions of the seafloor remains poorly understood. We conducted a series of experiments that elucidate the influence of excess density relative to flow velocity on the dynamics of, and depositional morphologies arising from, density currents undergoing sudden unconfinement across a sloped bed. Experimental currents transported only suspended sediment across a non-erodible substrate. Under flow conditions ranging from supercritical to subcritical (bulk Richardson numbers of 0.02 to 1.2) our experiments failed to produce deposits resembling or exhibiting the potential to evolve into self-formed leveed channels. In the absence of excess density, a submerged sediment-laden flow produced sharp crested lateral deposits bounding the margins of the flow for approximately a distance of two outlet widths down basin. These lateral deposits terminated in a centerline deposit that greatly exceeded marginal deposits in thickness. As excess density increased relative to the outlet velocity, the rate of lateral spreading of the flow increased relative to the downstream propagation of the density current, transitioning from a narrow flow aligned with the channel outlet to a broad radially expanding flow. Coincident with these changes in flow dynamics, the bounding lateral deposits extended for shorter distances, had lower, more poorly defined crests that were increasingly wider in separation than the initial outlet, and progressively became more oblong rather than linear. Based on our results, we conclude that leveed channels cannot initiate from sediment-laden density currents under strictly depositional conditions. Partial confinement of these currents appears to be necessary to establish the hydrodynamic conditions needed for sediment deposition along the margins of a density current which ultimately may evolve into confining levees. We suggest that erosion into a previously unchannelized substrate is the mostly likely source of this partial confinement.
EMC/FDTD/MD FOR MULTIPHYSICS CHARACTERIZATION OF SEMICONDUCTORS AT THZ FREQUENCIES
Knezevic, Irena
EMC/FDTD/MD FOR MULTIPHYSICS CHARACTERIZATION OF SEMICONDUCTORS AT THZ FREQUENCIES by Keely Willis.1 Ensemble Monte Carlo (EMC) . . . . . . . . . . . . . . . . . . . . . . . . . . . 14 2.2 Finite difference) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 19 3 EMC/FDTD for 2D analysis of materials with low carrier density . . . . . . . . . 22 3.1 EMC
Water adsorption on stepped ZnO surfaces from MD simulation David Raymand a
Goddard III, William A.
Water adsorption on stepped ZnO surfaces from MD simulation David Raymand a , Adri C.T. van Duin b Keywords: Zinc oxide Water SolidÂgas interfaces Construction and use of effective interatomic interactions force-field for use in molecular dynamics simulations of the ZnOÂ water system. The force
Modelling of the internal dynamics and density in a tens of joules plasma focus device
Marquez, Ariel [CNEA and Instituto Balseiro, 8402 Bariloche (Argentina); Gonzalez, Jose [INVAP-CONICET and Instituto Balseiro, 8402 Bariloche, Argentina. (Argentina); Tarifeno-Saldivia, Ariel; Pavez, Cristian; Soto, Leopoldo [CCHEN, Comision Chilena de Energia Nuclear, Casilla 188-D, Santiago (Chile); Center for Research and Applications in Plasma Physics and Pulsed Power, P4 (Chile); Clausse, Alejandro [CNEA-CONICET and Universidad Nacional del Centro, 7000 Tandil (Argentina)
2012-01-15T23:59:59.000Z
Using MHD theory, coupled differential equations were generated using a lumped parameter model to describe the internal behaviour of the pinch compression phase in plasma focus discharges. In order to provide these equations with appropriate initial conditions, the modelling of previous phases was included by describing the plasma sheath as planar shockwaves. The equations were solved numerically, and the results were contrasted against experimental measurements performed on the device PF-50J. The model is able to predict satisfactorily the timing and the radial electron density profile at the maximum compression.
Heart Valve Disease James S. Gammie, MD
Weber, David J.
Heart Valve Disease James S. Gammie, MD Professor and Chief Division of Cardiac Surgery University USA Source: CDC #12;#12;CARDIOTHORACIC SURGEON: A SURGEON THAT TREATS HEART AND LUNG DISEASE #12;Valvular Heart Disease: Common and Under-diagnosed 0 2 4 6 8 10 12 14 18 - 44 45 - 54 55 - 64 65 - 74 > 75
Strategic Plan Update Lydia Pleotis Howell MD
Leistikow, Bruce N.
diagnostic testing that is tailored to the prevention and management of disease. 4. Develop a culture....where are we at and what have we accomplished?? #12; Maximized resources, efficiency and effectiveness CultureStrategic Plan Update 2014-2015 Lydia Pleotis Howell MD Professor and Chair Pathology
Strategic Plan Update Lydia Pleotis Howell MD
Leistikow, Bruce N.
diagnostic testing that is tailored to the prevention and management of disease. 4. Develop a culture....where are we at and what have we accomplished?? #12; Maximized resources, efficiency and effectiveness CultureStrategic Plan Update 2013-2014 Lydia Pleotis Howell MD Professor and Chair Pathology
Marylee M. Rothschild, MD Louisville, Kentucky
, which results in respiratory problems from indoor air pollution as well as burns. HELPS has installed Brookfield, Wisconsin Daniel L. Wegg, MD Winchester, Indiana Brett A. Wyrick, DO Hilo, Hawaii Solomon Adu the health effects of the stove program through a comparison of medical diagnoses before and after
NIST, Gaithersburg, MD Green Auditorium, Bldg101
MBE Summit NIST, Gaithersburg, MD Green Auditorium, Bldg101 Time Topic Speaker(s) 0830 Cauley, HII-Ingalls NIST MBE Activities Simon Frechette, NIST 0940-1010 Smart Manufacturing Overviews FY14 1100-1115 Partnership for Research & Innovation in Sustainable Manufacturing Process, & System
Community Academic Profile Jon D. Fuller, MD
Ford, James
-1987 University of Utah School of Medicine MD Salt Lake City, Utah 1979-1983 University of Wyoming BS with honors-2001 Education & Community Professional Education Fellowship, Charles A. Dana. Foundation Fellowship Laramie, Wyoming Zoology/Physiology PROFESSIONAL TRAINING 1992-1993 Stanford University Charles A. Dana
Morzan, Uriel N.; Ramírez, Francisco F.; Scherlis, Damián A., E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Departamento de Química Inorgánica, Analítica y Química Física/INQUIMAE, Facultad de Ciencias Exactas y Naturales, Universidad de Buenos Aires, Ciudad Universitaria, Pab. II, Buenos Aires (C1428EHA) (Argentina); Oviedo, M. Belén; Sánchez, Cristián G. [Departamento de Matemática y Física, Facultad de Ciencias Químicas, INFIQC, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba (Argentina)] [Departamento de Matemática y Física, Facultad de Ciencias Químicas, INFIQC, Universidad Nacional de Córdoba, Ciudad Universitaria, X5000HUA Córdoba (Argentina); Lebrero, Mariano C. González, E-mail: damian@qi.fcen.uba.ar, E-mail: mcgl@qb.ffyb.uba.ar [Instituto de Química y Fisicoquímica Biológicas, IQUIFIB, CONICET (Argentina)] [Instituto de Química y Fisicoquímica Biológicas, IQUIFIB, CONICET (Argentina)
2014-04-28T23:59:59.000Z
This article presents a time dependent density functional theory (TDDFT) implementation to propagate the Kohn-Sham equations in real time, including the effects of a molecular environment through a Quantum-Mechanics Molecular-Mechanics (QM-MM) hamiltonian. The code delivers an all-electron description employing Gaussian basis functions, and incorporates the Amber force-field in the QM-MM treatment. The most expensive parts of the computation, comprising the commutators between the hamiltonian and the density matrix—required to propagate the electron dynamics—, and the evaluation of the exchange-correlation energy, were migrated to the CUDA platform to run on graphics processing units, which remarkably accelerates the performance of the code. The method was validated by reproducing linear-response TDDFT results for the absorption spectra of several molecular species. Two different schemes were tested to propagate the quantum dynamics: (i) a leap-frog Verlet algorithm, and (ii) the Magnus expansion to first-order. These two approaches were confronted, to find that the Magnus scheme is more efficient by a factor of six in small molecules. Interestingly, the presence of iron was found to seriously limitate the length of the integration time step, due to the high frequencies associated with the core-electrons. This highlights the importance of pseudopotentials to alleviate the cost of the propagation of the inner states when heavy nuclei are present. Finally, the methodology was applied to investigate the shifts induced by the chemical environment on the most intense UV absorption bands of two model systems of general relevance: the formamide molecule in water solution, and the carboxy-heme group in Flavohemoglobin. In both cases, shifts of several nanometers are observed, consistently with the available experimental data.
Mentel, ?. M.; Meer, R. van; Gritsenko, O. V. [Section Theoretical Chemistry, VU University, Amsterdam (Netherlands); Pohang University of Science and Technology, Pohang (Korea, Republic of); Baerends, E. J. [Section Theoretical Chemistry, VU University, Amsterdam (Netherlands); Pohang University of Science and Technology, Pohang (Korea, Republic of); Chemistry Department, Faculty of Science, King Abdulaziz University, Jeddah 21589 (Saudi Arabia)
2014-06-07T23:59:59.000Z
For chemistry an accurate description of bond weakening and breaking is vital. The great advantage of density matrix functionals, as opposed to density functionals, is their ability to describe such processes since they naturally cover both nondynamical and dynamical correlation. This is obvious in the Löwdin-Shull functional, the exact natural orbital functional for two-electron systems. We present in this paper extensions of this functional for the breaking of a single electron pair bond in N-electron molecules, using LiH, BeH{sup +}, and Li{sub 2} molecules as prototypes. Attention is given to the proper formulation of the functional in terms of not just J and K integrals but also the two-electron L integrals (K integrals with a different distribution of the complex conjugation of the orbitals), which is crucial for the calculation of response functions. Accurate energy curves are obtained with extended Löwdin-Shull functionals along the complete dissociation coordinate using full CI calculations as benchmark.
C. L. Zhou; Y. G. Ma; D. Q. Fang; G. Q. Zhang
2012-12-20T23:59:59.000Z
Thermodynamic and transport properties of nuclear fireball created in the central region of heavy-ion collisions below 400 MeV/nucleon are investigated within the isospin-dependent quantum molecular dynamic (IQMD) model. These properties including the density, temperature, chemical potential, entropy density ($s$) and shear viscosity ($\\eta$), are calculated by a generalized hot Thomas Fermi formulism and a parameterized function, which was developed by Danielewicz. As the collision goes on, a transient minimal $\\eta/s=5/4\\pi-10/4\\pi$ occurs in the largest compression stage. Besides, the relationship of $\\eta/s$ to temperature ($T$) in the freeze-out stage displays a local minimum which is about 9-20 times $1/4\\pi$ around $T$ = 8-12 MeV, which can be argued as indicative of a liquid gas phase transition. In addition, the influences of nucleon-nucleon (NN) cross section ($\\sigma_{NN}$) and symmetry energy coefficient ($C_{s}$) are also discussed, and it is found that the results are sensitive to $\\sigma_{NN}$ but not to $C_{s}$.
Free Energy Calculation in MD Simulation
Nielsen, Steven O.
Free Energy Calculation in MD Simulation #12;Basic Thermodynamics Helmoholtz free energy A = U Â TS + i Ni dA = wrev (reversible, const N V T) eq (22.9) McQuarrie & Simon Gibbs free energy G = U;Implication of Free Energy A B Keq = [A]/[B] Keq = exp (-G0 /RT) G0 = -RT ln Keq G = G0 + RT ln Q G > 0
Ultrafast dynamics of a near-solid-density layer in an intense femtosecond laser-excited plasma
Adak, Amitava; Chatterjee, Gourab; Kumar Singh, Prashant; Lad, Amit D.; Brijesh, P.; Kumar, G. Ravindra, E-mail: grk@tifr.res.in [Tata Institute of Fundamental Research, Dr. Homi Bhabha Road, Colaba, Mumbai 400005 (India); Blackman, David R. [York Plasma Institute, University of York, Heslington, York YO10 5DQ (United Kingdom); Robinson, A. P. L. [Central Laser Facility, Rutherford-Appleton Laboratory, Chilton, Didcot OX10 0QX (United Kingdom); Pasley, John [York Plasma Institute, University of York, Heslington, York YO10 5DQ (United Kingdom); Central Laser Facility, Rutherford-Appleton Laboratory, Chilton, Didcot OX10 0QX (United Kingdom)
2014-06-15T23:59:59.000Z
We report on the picosecond dynamics of a near-solid-density plasma generated by an intense, infrared (??=?800?nm) femtosecond laser using time-resolved pump-probe Doppler spectrometry. An initial red-shift is observed in the reflected third harmonic (??=?266?nm) probe pulse, which gets blue-shifted at longer probe-delays. A combination of particle-in-cell and radiation-hydrodynamics modelling is performed to model the pump laser interaction with the solid target. The results are post-processed to predict the Doppler shift. An excellent agreement is found between the results of such modelling and the experiment. The modelling suggests that the initial inward motion of the critical surface observed in the experiment is due to the passage of a shock-wave-like disturbance, launched by the pump interaction, propagating into the target. Furthermore, in order to achieve the best possible fit to the experimental data, it was necessary to incorporate the effects of bulk ion-acceleration resulting from the electrostatic field set up by the expulsion of electrons from the laser envelope. We also present results of time-resolved pump-probe reflectometry, which are corroborated with the spectrometry results using a 1-D reflectivity model.
Ad hoc continuum-atomistic thermostat for modeling heat flow in molecular dynamics simulations
Brenner, Donald W.
Ad hoc continuum-atomistic thermostat for modeling heat flow in molecular dynamics simulations J 2004) An ad hoc thermostating procedure that couples a molecular dynamics (MD) simulation
Lichtarge, Olivier
Phenomenology of Psychogenic Movement Disorders in Children Joseph Ferrara, MD and Joseph Jankovic little has been published regarding the frequency and phenomenology of PMDs in children. We reviewed (61) 14 (26) 7 (13) Objective: To assess the frequency and phenomenology of psychogenic movement
Recipient. County of Baltimore, MD ENERGY EFFICIENCY AND CONSERVATION...
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40 Recipient. County of Baltimore, MD ENERGY EFFICIENCY AND CONSERVATION BLOCK GRANTS NEPA COMPLIANCE FORM Activities Determination Categorical Exclusion Reviewer's Specific...
Evaluation of Powertrain Options and Component Sizing for MD...
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
Sizing for MD and HD Applications on Real World Drive Cycles 2011 DOE Hydrogen and Fuel Cells Program, and Vehicle Technologies Program Annual Merit Review and Peer...
Alexis Diaz-Torres
2010-10-18T23:59:59.000Z
The coupled-channels density-matrix technique for nuclear reaction dynamics, which is based on the Liouville-von Neumann equation with Lindblad dissipative terms, is developed with the inclusion of full angular momentum couplings. It allows a quantitative study of the role and importance of quantum decoherence in nuclear scattering. Formulae of asymptotic observables that can reveal effects of quantum decoherence are given. A method for extracting energy-resolved scattering information from the time-dependent density matrix is introduced. As an example, model calculations are carried out for the low-energy collision of the $^{16}$O projectile on the $^{154}$Sm target.
Introduction to Molecular Dynamics and Accelerated Molecular Dynamics
Perez, Danny [Los Alamos National Laboratory
2012-06-25T23:59:59.000Z
We first introduce classical molecular dynamics (MD) simulations. We discuss their main constituents - the interatomic potentials, the boundary conditions, and the integrators - and the discuss the various ensembles that can be sampled. We discuss the strengths and weaknesses of MD, specifically in terms of time and length-scales. We then move on to discuss accelerated MD (AMD) methods, techniques that were designed to circumvent the timescale limitations of MD for rare event systems. The different methods are introduced and examples of use given.
Fuini, John F
2015-01-01T23:59:59.000Z
Using holography, we study the evolution of a spatially homogeneous, far from equilibrium, strongly coupled N=4 supersymmetric Yang-Mills plasma with a non-zero charge density or a background magnetic field. This gauge theory problem corresponds, in the dual gravity description, to an initial value problem in Einstein-Maxwell theory with homogeneous but anisotropic initial conditions. We explore the dependence of the equilibration process on different aspects of the initial departure from equilibrium and, while controlling for these dependencies, examine how the equilibration dynamics are affected by the presence of a non-vanishing charge density or an external magnetic field. The equilibration dynamics are remarkably insensitive to the addition of even large chemical potentials or magnetic fields; the equilibration time is set primarily by the form of the initial departure from equilibrium. For initial deviations from equilibrium which are well localized in scale, we formulate a simple model for equilibratio...
John F. Fuini III; Laurence G. Yaffe
2015-03-24T23:59:59.000Z
Using holography, we study the evolution of a spatially homogeneous, far from equilibrium, strongly coupled N=4 supersymmetric Yang-Mills plasma with a non-zero charge density or a background magnetic field. This gauge theory problem corresponds, in the dual gravity description, to an initial value problem in Einstein-Maxwell theory with homogeneous but anisotropic initial conditions. We explore the dependence of the equilibration process on different aspects of the initial departure from equilibrium and, while controlling for these dependencies, examine how the equilibration dynamics are affected by the presence of a non-vanishing charge density or an external magnetic field. The equilibration dynamics are remarkably insensitive to the addition of even large chemical potentials or magnetic fields; the equilibration time is set primarily by the form of the initial departure from equilibrium. For initial deviations from equilibrium which are well localized in scale, we formulate a simple model for equilibration times which agrees quite well with our results.
Chu, Shih-I
for electron transport dynamics in molecular devices Zhongyuan Zhou(a) and Shih-I Chu Department of Chemistry and structures PACS 85.65.+h Â Molecular electronic devices PACS 71.15.Pd Â Molecular dynamics calculations (Carr) approach in momentum (P) space for the study of electron transport in molecular devices under arbitrary
Serial Intraoperative MR Imaging of Brain Shift Arya Nabavi, M.D.1
Serial Intraoperative MR Imaging of Brain Shift Arya Nabavi, M.D.1 , Peter McL. Black, M.D. Ph.D.1 , David T. Gering, M.S.4 , Carl-Fredrik Westin, Ph.D3 , Vivek Mehta, M.D.1 , Richard S. Pergolizzi Jr., M, M.D., Ph.D.2 , William M. Wells III, Ph.D4 ., Ron Kikinis, M.D.3 , Ferenc A. Jolesz, M.D.3 1
Chu, Shih-I; Zhou, Zhongyuan
2009-10-27T23:59:59.000Z
We propose a time-dependent density functional theoretical (TDDFT) approach in momentum (\\mathcal{P} ) space for the study of electron transport in molecular devices under arbitrary biases. The basic equation of motion, which is a time...
Foroutan, G. [Department of Physics, Faculty of Science, Sahand University of Technology, Tabriz 51335-1996 (Iran, Islamic Republic of); School of Physics, The University of Sydney, Sydney NSW 2006 (Australia); Khalilpour, H.; Moslehi-Fard, M. [Faculty of Physics, Tabriz University, Tabriz 51664 (Iran, Islamic Republic of); Li, B.; Robinson, P. A. [School of Physics, University of Sydney, Sydney NSW 2006 (Australia)
2008-12-15T23:59:59.000Z
The effects of plasma inhomogeneities on the propagation of a cloud of hot electrons through a cold background plasma and generation of Langmuir waves are investigated using numerical simulations of the quasilinear equations. It is found that in a plasma with decreasing density the quasilinear relaxation of the electron distribution in velocity space is accelerated and the levels of the generated Langmuir waves are enhanced. The magnitude of the induced emission rate is increased and its maximum value moves to lower velocities. Due to density gradient the height of plateau shows an increase at small distances and a corresponding decrease at large distances. It is also found that in a plasma with decreasing temperature, the relaxation of the beam is retarded, the spectral density of Langmuir waves is broadened, and the height of the plateau decreases below its value in a uniform plasma. In the presence of both density and temperature gradients, at given position, the height and upper boundary of the plateau and the level of Langmuir waves are all increased at small velocities. The spatial expansion of the beam is increased by the plasma inhomogeneities, but its average velocity of propagation decreases. Initially, at a given position, the velocity at the upper boundary of the plateau is smaller in the presence of the density gradient than in the uniform plasma but the reverse is true at longer times. Due to temperature gradient, at large times and small distances, the upper boundary of the plateau is increased above its value in the uniform plasma. Because of fast relaxation, the value of the lower boundary of the plateau in the plasma with decreasing density is always less than its value in the uniform plasma. It is found that the local velocity of the beam decreases when the density gradient is present. The local velocity spread of the beam remains unchanged during the propagation of the beam in the uniform plasma, but increases in the presence of inhomogeneities.
A molecular dynamics study of polymer/graphene interfacial systems
Rissanou, Anastassia N.; Harmandaris, Vagelis [Department of Mathematics and Applied Mathematics, University of Crete, GR-71409, Heraklion, Crete, Greece and Institute of Applied and Computational Mathematics (IACM), Foundation for Research and Technology Hellas (FORTH), GR-71110, Heraklion, Cret (Greece)
2014-05-15T23:59:59.000Z
Graphene based polymer nanocomposites are hybrid materials with a very broad range of technological applications. In this work, we study three hybrid polymer/graphene interfacial systems (polystyrene/graphene, poly(methyl methacrylate)/graphene and polyethylene/graphene) through detailed atomistic molecular dynamics (MD) simulations. Density profiles, structural characteristics and mobility aspects are being examined at the molecular level for all model systems. In addition, we compare the properties of the hybrid systems to the properties of the corresponding bulk ones, as well as to theoretical predictions.
Wang, Weihuang
2009-05-15T23:59:59.000Z
This thesis presents a low-power LDPC decoder design based on speculative scheduling of energy necessary to decode dynamically varying data frame in both block-fading channels and general AWGN channels. A model of a memory-efficient low-power high...
Eder, R.; Ohta, Y. [Department of Applied Physics, Nagoya University, Nagoya 464-01 (Japan)] [Department of Applied Physics, Nagoya University, Nagoya 464-01 (Japan)
1995-05-01T23:59:59.000Z
We present an exact diagonalization study of the dynamical spin and density correlation functions in small clusters of the {ital t}-{ital J} model, focusing on the regime of intermediate and low electron densities, {rho}{sub {ital e}}{lt}0.5. In two dimensions (2D) both correlation functions agree remarkably well with the convolution of the single-particle spectral function, i.e., the simplest estimate possible within a Fermi-liquid picture. Deviations from the convolution are shown to originate from symmetry-related selection rules, which are unaccounted for in the convolution estimate. For all fillngs under consideration, we show that the low-energy peaks originate from particle-hole excitations between the Fermi momenta, as expected for a Fermi liquid. We contrast this with the behavior in 1D, where spin and density correlation function show the differences characteristic of spin-charge separation and where neither correlation function is approximated well by the convolution.
Hussein, Ibnelwaleed A.
of Branched Polyethylene Chains with Uniform Branch Distribution I. A. HUSSEIN, B. F. ABU-SHARKH* Department-density polyethylene (LLDPE) chains with different levels of branch content (BC), ranging from 10 to 80 branches/1000 C words: MD simulation, Polyethylene, branch content, chain conformation, radius of gyration
Stránský, Pavel [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovi?kách 2, 18000 Prague (Czech Republic); Instituto de Ciencias Nucleares, Universidad Nacional Autónoma de México, 04510, México, D.F. (Mexico); Macek, Michal [Racah Institute of Physics, The Hebrew University, 91904 Jerusalem (Israel); Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovi?kách 2, 18000 Prague (Czech Republic); Cejnar, Pavel, E-mail: pavel.cejnar@mff.cuni.cz [Institute of Particle and Nuclear Physics, Faculty of Mathematics and Physics, Charles University, V Holešovi?kách 2, 18000 Prague (Czech Republic)
2014-06-15T23:59:59.000Z
Quantum systems with a finite number of freedom degrees f develop robust singularities in the energy spectrum of excited states as the system’s size increases to infinity. We analyze the general form of these singularities for low f, particularly f=2, clarifying the relation to classical stationary points of the corresponding potential. Signatures in the smoothed energy dependence of the quantum state density and in the flow of energy levels with an arbitrary control parameter are described along with the relevant thermodynamical consequences. The general analysis is illustrated with specific examples of excited-state singularities accompanying the first-order quantum phase transition. -- Highlights: •ESQPTs found in infinite-size limit of systems with low numbers of freedom degrees f. •ESQPTs related to non-analytical evolutions of classical phase–space properties. •ESQPT signatures analyzed for general f, particularly f=2, extending known case f=1. •ESQPT signatures identified in smoothened density and flow of energy spectrum. •ESQPTs shown to induce a new type of thermodynamic anomalies.
Tirthankar Dutta; S. Ramasesha
2011-12-29T23:59:59.000Z
We investigate the effect of static electron-phonon coupling, on real-time dynamics of spin and charge transport in $\\pi$-conjugated polyene chains. The polyene chain is modeled by the Pariser-Parr-Pople Hamiltonian with dimerized nearest-neighbor parameter $t_{0}(1+\\delta)$ for short bonds and $t_{0}(1-\\delta)$ for long bonds, and long-range electron-electron interactions. We follow the time evolution of the spin and charge using time-dependent density matrix renormalization group technique, when a hole is injected at one end of the chain in its ground state. We find that spin and charge dynamics followed through spin and charge velocities, depend both on chain length and extent of dimerization, $\\delta$. Analysis of the results requires focusing on physical quantities such as average spin and charge polarizations, particularly in the large dimerization limit. In the dimerization range 0.0 $\\le$ $\\delta$ $\\le$ 0.15, spin-charge dynamics is found to have a well defined behavior, with spin-charge separation (measured as the ratio of charge velocity to spin velocity) as well as, the total amount of charge and spin transported in a given time, along the chain, decreasing as dimerization increases. However, in the range 0.3 $\\le$ $\\delta$ $\\le$ 0.5, it is observed that the dynamics of spin and charge transport becomes complicated. It is observed that for large $\\delta$ values, spin-charge separation is suppressed and the injected hole fails to travel the entire length of the chain.
Substructured multibody molecular dynamics.
Grest, Gary Stephen; Stevens, Mark Jackson; Plimpton, Steven James; Woolf, Thomas B. (Johns Hopkins University, Baltimore, MD); Lehoucq, Richard B.; Crozier, Paul Stewart; Ismail, Ahmed E.; Mukherjee, Rudranarayan M. (Rensselaer Polytechnic Institute, Troy, NY); Draganescu, Andrei I.
2006-11-01T23:59:59.000Z
We have enhanced our parallel molecular dynamics (MD) simulation software LAMMPS (Large-scale Atomic/Molecular Massively Parallel Simulator, lammps.sandia.gov) to include many new features for accelerated simulation including articulated rigid body dynamics via coupling to the Rensselaer Polytechnic Institute code POEMS (Parallelizable Open-source Efficient Multibody Software). We use new features of the LAMMPS software package to investigate rhodopsin photoisomerization, and water model surface tension and capillary waves at the vapor-liquid interface. Finally, we motivate the recipes of MD for practitioners and researchers in numerical analysis and computational mechanics.
Leroy, Frédéric, E-mail: f.leroy@theo.chemie.tu-darmstadt.de; Böhm, Michael C., E-mail: boehm@theo.chemie.tu-darmstadt.de [Eduard-Zintl-Institut für Anorganische und Physikalische Chemie, Technische Universität Darmstadt, D-64287 Darmstadt (Germany); Schulte, Joachim [Bruker Biospin GmbH, Silberstreifen, D-76287 Rheinstetten (Germany)] [Bruker Biospin GmbH, Silberstreifen, D-76287 Rheinstetten (Germany); Balasubramanian, Ganesh [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)] [Department of Mechanical Engineering, Iowa State University, Ames, Iowa 50011 (United States)
2014-04-14T23:59:59.000Z
We report reverse nonequilibrium molecular dynamics calculations of the thermal conductivity of isotope substituted (10,10) carbon nanotubes (CNTs) at 300 K. {sup 12}C and {sup 14}C isotopes both at 50% content were arranged either randomly, in bands running parallel to the main axis of the CNTs or in bands perpendicular to this axis. It is found that the systems with randomly distributed isotopes yield significantly reduced thermal conductivity. In contrast, the systems where the isotopes are organized in patterns parallel to the CNTs axis feature no reduction in thermal conductivity when compared with the pure {sup 14}C system. Moreover, a reduction of approximately 30% is observed in the system with the bands of isotopes running perpendicular to the CNT axis. The computation of phonon dispersion curves in the local density approximation and classical densities of vibrational states reveal that the phonon structure of carbon nanotubes is conserved in the isotope substituted systems with the ordered patterns, yielding high thermal conductivities in spite of the mass heterogeneity. In order to complement our conclusions on the {sup 12}C-{sup 14}C mixtures, we computed the thermal conductivity of systems where the {sup 14}C isotope was turned into pseudo-atoms of 20 and 40 atomic mass units.
LSUHSC NO Leadership Program Director, Augusto Ochoa, MD
D: Project 8 Yan Cui, PhD: COBRE Graduate Mentor Internal Advisory Committee Joseph Moerschbaecher, III: Jonna Ellis Promising Junior Investigators Project 2: Jovanny Zabaleta, PhD Project 3: Paulo Rodriguez, PhD Project 4: Timothy Foster, PhD Project 5: John Schieffelin, MD Tulane University Project 6
GRANT AWARDS Justin Annes, MD, PhD
Bejerano, Gill
Therapy POSTDOCS AWARDS Joseph Cheng, PhD, MEng, BS Postdoctoral fellow, Radiology Pediatric Radiology, Pediatrics Gastroenterology Project: Translational Studies using Immune and Microbiota markers in Vancomycin-treated Children with GI disease Adam Frymoyer, MD Instructor, Pediatrics General Pediatrics & Neonatal
Joseph P. Vacanti, MD Chief of Pediatric Surgery
Mootha, Vamsi K.
, neurosurgery, radiology, pediatric intensive care, genetic counseling, social work and palliative careJoseph P. Vacanti, MD Chief of Pediatric Surgery and Surgeon-in-Chief MassGeneral Hospital Pediatrics Debra Burke, RN, MSN, MBA Associate Chief Nurse Chiefs' Notes To provide optimal support
MD6151-8-10 Murdoch Counselling Service
MD6151-8-10 Murdoch Counselling Service Stress management What is stress? Stress is the way your to gather physical and emotional energy which helps you deal with changes and challenges in your daily life which drains you of emotional and physical energy. How is university stressful? University life can
Asbestos-related diseases in automobile mechanics Jacques Ameille, MD1
Paris-Sud XI, UniversitÃ© de
1 Asbestos-related diseases in automobile mechanics Jacques Ameille, MD1 , Nicole Rosenberg, MD2-related diseases in automobile mechanics Corresponding author Jacques Ameille, MD, UnitÃ© de pathologie plaques, automobile mechanics, HRCT inserm-00671970,version1-20Feb2012 Author manuscript, published
COMMISSION ON HEALTH SCIENCE, EDUCATION, AND P. Roy Vagelos, M.D.
Lin, Xiaodong
Johnson & Johnson Barbara Bell Coleman Chairperson Amelior Foundation Norman H. Edelman, M.D. Vice Princeton University Steven A. Schroeder, M.D. President and CEO The Robert Wood Johnson Foundation Harold and Dentistry of New Jersey Samuel O. Thier, M.D. President and CEO Partners HealthCare System, Inc. #12
Research Paper j Using Petri Net Tools to Study Properties and Dynamics of
Rubin, Daniel L.
Research Paper j Using Petri Net Tools to Study Properties and Dynamics of Biological Systems MOR PELEG, PHD, DANIEL RUBIN, MD, MSC, RUSS B. ALTMAN, MD, PHD A b s t r a c t Petri Nets (PNs concurrent dynamic systems is Petri Nets (PNs).1 An advantage of PNs is that they can represent system
Bolinger, Joshua C.; Bixby, Teresa J.; Reid, Philip J. [Box 351700, Department of Chemistry, University of Washington, Seattle, Washington 98195 (United States)
2005-08-22T23:59:59.000Z
We report a series of time-resolved infrared absorption studies on chlorine dioxide (OClO) dissolved in H{sub 2}O, D{sub 2}O, and acetonitrile. Following the photoexcitation at 401 nm, the evolution in optical density for frequencies corresponding to asymmetric stretch of OClO is measured with a time resolution of 120{+-}50 fs. The experimentally determined optical-density evolution is compared with theoretical models of OClO vibrational relaxation derived from collisional models as well as classical molecular-dynamics (MD) studies. The vibrational relaxation rates in D{sub 2}O are reduced by a factor of 3 relative to H{sub 2}O consistent with the predictions of MD. This difference reflects modification of the frequency-dependent solvent-solute coupling accompanying isotopic substitution of the solvent. Also, the geminate-recombination quantum yield for the primary photofragments resulting in the reformation of ground-state OClO is reduced in D{sub 2}O relative to H{sub 2}O. It is proposed that this reduction reflects enhancement of the dissociation rate accompanying vibrational excitation along the asymmetric-stretch coordinate. In contrast to H{sub 2}O and D{sub 2}O, the vibrational-relaxation dynamics in acetonitrile are not well described by the theoretical models. Reproduction of the optical-density evolution in acetonitrile requires significant modification of the frequency-dependent solvent-solute coupling derived from MD. It is proposed that this modification reflects vibrational-energy transfer from the asymmetric stretch of OClO to the methyl rock of acetonitrile. In total, the results presented here provide a detailed description of the solvent-dependent geminate-recombination and vibrational-relaxation dynamics of OClO in solution.
Duan, Yuhua; Parlinski, K.
2011-01-01T23:59:59.000Z
The structural, electronic, lattice dynamical, optical, thermodynamic, and CO{sub 2} capture properties of monoclinic and triclinic phases of Li{sub 4}SiO{sub 4} are investigated by combining density functional theory with phonon lattice dynamics calculations. We found that these two phases have some similarities in their bulk and thermodynamic properties. The calculated bulk modulus and the cohesive energies of these two phases are close to each other. Although both of them are insulators, the monoclinic phase of Li{sub 4}SiO{sub 4} has a direct band gap of 5.24 eV while the triclinic Li{sub 4}SiO{sub 4} phase has an indirect band gap of 4.98 eV. In both phases of Li{sub 4}SiO{sub 4}, the s orbital of O mainly contributes to the lower-energy second valence band (VB{sub 2}) and the p orbitals contribute to the fist valence band (VB{sub 1}) and the conduction bands (CBs). The s orbital of Si mainly contributes to the lower portions of the VB1 and VB{sub 2}, and Si p orbitals mainly contribute to the higher portions of the VB{sub 1} and VB{sub 2}. The s and p orbitals of Li contribute to both VBs and to CBs, and Li p orbitals have a higher contribution than the Li s orbital. There is possibly a phonon soft mode existing in triclinic {gamma}-Li{sub 4}SiO{sub 4}; in the monoclinic Li{sub 4}SiO{sub 4}, there are three phonon soft modes, which correspond to the one type of Li disordered over a few sites. Their LO-TO splitting indicates that both phases of Li{sub 4}SiO{sub 4} are polar anisotropic materials. The calculated infrared absorption spectra for LO and TO modes are different for these two phases of Li{sub 4}SiO{sub 4}. The calculated relationships of the chemical potential versus temperature and CO{sub 2} pressure for reaction of Li{sub 4}SiO{sub 4} with CO{sub 2} shows that Li{sub 4}SiO{sub 4} could be a good candidate for a high-temperature CO{sub 2} sorbent while used for postcombustion capture technology.
Nehorai, Arye
Brain-Computer Interfaces in Medicine Jerry J. Shih, MD; Dean J. Krusienski, PhD; and Jonathan R. Wolpaw, MD Abstract Brain-computer interfaces (BCIs) acquire brain signals, analyze them, and translate, electrocorticographic, and other brain signals for increasingly complex control of cursors, robotic arms, prostheses
Hydration structure of salt solutions from ab initio molecular dynamics
Bankura, Arindam; Carnevale, Vincenzo; Klein, Michael L. [Institute for Computational Molecular Science and Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States)
2013-01-07T23:59:59.000Z
The solvation structures of Na{sup +}, K{sup +}, and Cl{sup -} ions in aqueous solution have been investigated using density functional theory (DFT) based Car-Parrinello (CP) molecular dynamics (MD) simulations. CPMD trajectories were collected for systems containing three NaCl or KCl ion pairs solvated by 122 water molecules using three different but commonly employed density functionals (BLYP, HCTH, and PBE) with electron correlation treated at the level of the generalized gradient approximation (GGA). The effect of including dispersion forces was analyzed through the use of an empirical correction to the DFT-GGA scheme. Special attention was paid to the hydration characteristics, especially the structural properties of the first solvation shell of the ions, which was investigated through ion-water radial distribution functions, coordination numbers, and angular distribution functions. There are significant differences between the present results obtained from CPMD simulations and those provided by classical MD based on either the CHARMM force field or a polarizable model. Overall, the computed structural properties are in fair agreement with the available experimental results. In particular, the observed coordination numbers 5.0-5.5, 6.0-6.4, and 6.0-6.5 for Na{sup +}, K{sup +}, and Cl{sup -}, respectively, are consistent with X-ray and neutron scattering studies but differ somewhat from some of the many other recent computational studies of these important systems. Possible reasons for the differences are discussed.
Lan, Tian [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Li, Chen [ORNL] [ORNL; Niedziela, Jennifer L [ORNL] [ORNL; Smith, Hillary [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Abernathy, Douglas L [ORNL] [ORNL; Rossman, George [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena; Fultz, B. [California Institute of Technology, Pasadena] [California Institute of Technology, Pasadena
2014-01-01T23:59:59.000Z
Inelastic neutron scattering measurements on silver oxide (Ag2O) with the cuprite structure were performed at temperatures from 40 to 400 K, and Fourier transform far-infrared spectra were measured from 100 to 300 K. The measured phonon densities of states and the infrared spectra showed unusually large energy shifts with temperature, and large linewidth broadenings. First principles molecular dynamics (MD) calculations were performed at various temperatures, successfully accounting for the negative thermal expansion (NTE) and local dynamics. Using the Fourier-transformed velocity autocorrelation method, the MD calculations reproduced the large anharmonic effects of Ag2O, and were in excellent agreement with the neutron scattering data. The quasiharmonic approximation (QHA) was less successful in accounting for much of the phonon behavior. The QHA could account for some of the NTE below 250 K, although not at higher temperatures. Strong anharmonic effects were found for both phonons and for the NTE. The lifetime broadenings of Ag2O were explained by anharmonic perturbation theory, which showed rich interactions between the Ag-dominated modes and the O-dominated modes in both up- and down-conversion processes.
MD/HD Advanced Technology Evaluations | Department of Energy
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Office of Inspector General Office0-72.pdfGeorgeDoesn't HappenLow-Cost Production ofModelingfor theMACCS2ofMD/HD
Pan, Jianjun [University of South Florida, Tampa (USF)] [University of South Florida, Tampa (USF); Cheng, Xiaolin [ORNL] [ORNL; Monticelli, Luca [Institut National de la Santé et de la Recherche Médicale (INSERM) and INTS, France] [Institut National de la Santé et de la Recherche Médicale (INSERM) and INTS, France; Heberle, Frederick A [ORNL] [ORNL; Kucerka, Norbert [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,] [Atomic Energy of Canada Limited (AECL), Canadian Neutron Beam Centre (CNBC) and Comenius University,; Tieleman, D. Peter [University of Calgary, ALberta, Canada] [University of Calgary, ALberta, Canada; Katsaras, John [ORNL] [ORNL
2014-01-01T23:59:59.000Z
Phosphatidylserine (PS) lipids play essential roles in biological processes, including enzyme activation and apoptosis. We report on the molecular structure and atomic scale interactions of a fluid bilayer composed of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphatidylserine (POPS). A scattering density profile model, aided by molecular dynamics (MD) simulations, was developed to jointly refine different contrast small-angle neutron and X-ray scattering data, which yielded a lipid area of 62.7 A2 at 25 C. MD simulations with POPS lipid area constrained at different values were also performed using all-atom and aliphatic united-atom models. The optimal simulated bilayer was obtained using a model-free comparison approach. Examination of the simulated bilayer, which agrees best with the experimental scattering data, reveals a preferential interaction between Na+ ions and the terminal serine and phosphate moieties. Long-range inter-lipid interactions were identified, primarily between the positively charged ammonium, and the negatively charged carboxylic and phosphate oxygens. The area compressibility modulus KA of the POPS bilayer was derived by quantifying lipid area as a function of surface tension from area-constrained MD simulations. It was found that POPS bilayers possess a much larger KA than that of neutral phosphatidylcholine lipid bilayers. We propose that the unique molecular features of POPS bilayers may play an important role in certain physiological functions.
E-Print Network 3.0 - antioxidants bethesda md Sample Search...
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Content and Inflammatory Cytokines Tumor Necrosis Summary: Cells. Lipid O staining and Image-Pro analysis (Media Cybernetics, Inc., Bethesda, MD) revealed that h... in human...
Department of Materials Science and Engineering University of Maryland, College Park, MD
Rubloff, Gary W.
for engineering practice #12;Topics Covered: I. Electrical and Optical Properties--Organic Photovoltaics A. Introduction: Organic photovoltaics B. Ohm's law C. Energy bands and energy gaps D. Carrier density in metals and semiconductors E. Optical absorption in semiconductors F. Excitons -- Size, Energy, Dynamics G. PN junction H
Harry Greenspun, M.D. Senior Advisor, Health Care Transformation & Technology
Stanford, Kyle
Harry Greenspun, M.D. Senior Advisor, Health Care Transformation & Technology Deloitte Center for Health Solutions Deloitte LLP Bio highlights Harry Greenspun, M.D., is the Senior Advisor for Health Care a diverse range of clinical and executive roles, and is now responsible for helping Deloitte's health care
Molecular Dynamics Simulation of Macromolecules Using Graphics Processing Unit
Ji Xu; Ying Ren; Wei Ge; Xiang Yu; Xiaozhen Yang; Jinghai Li
2010-01-21T23:59:59.000Z
Molecular dynamics (MD) simulation is a powerful computational tool to study the behavior of macromolecular systems. But many simulations of this field are limited in spatial or temporal scale by the available computational resource. In recent years, graphics processing unit (GPU) provides unprecedented computational power for scientific applications. Many MD algorithms suit with the multithread nature of GPU. In this paper, MD algorithms for macromolecular systems that run entirely on GPU are presented. Compared to the MD simulation with free software GROMACS on a single CPU core, our codes achieve about 10 times speed-up on a single GPU. For validation, we have performed MD simulations of polymer crystallization on GPU, and the results observed perfectly agree with computations on CPU. Therefore, our single GPU codes have already provided an inexpensive alternative for macromolecular simulations on traditional CPU clusters and they can also be used as a basis to develop parallel GPU programs to further speedup the computations.
Molecular Dynamics Simulation of Thermodynamic Properties in Uranium Dioxide
Wang, Xiangyu; Wu, Bin; Gao, Fei; Li, Xin; Sun, Xin; Khaleel, Mohammad A.; Akinlalu, Ademola V.; Liu, L.
2014-03-01T23:59:59.000Z
In the present study, we investigated the thermodynamic properties of uranium dioxide (UO2) by molecular dynamics (MD) simulations. As for solid UO2, the lattice parameter, density, and enthalpy obtained by MD simulations were in good agreement with existing experimental data and previous theoretical predictions. The calculated thermal conductivities matched the experiment results at the midtemperature range but were underestimated at very low and very high temperatures. The calculation results of mean square displacement represented the stability of uranium at all temperatures and the high mobility of oxygen toward 3000 K. By fitting the diffusivity constant of oxygen with the Vogel-Fulcher-Tamman law, we noticed a secondary phase transition near 2006.4 K, which can be identified as a ‘‘strong’’ to ‘‘fragile’’ supercooled liquid or glass phase transition in UO2. By fitting the oxygen diffusion constant with the Arrhenius equation, activation energies of 2.0 and 2.7 eV that we obtained were fairly close to the recommended values of 2.3 to 2.6 eV. Xiangyu Wang, Bin Wu, Fei Gao, Xin Li, Xin Sun, Mohammed A. Khaleel, Ademola V. Akinlalu and Li Liu
Chu, Xi; Chu, Shih-I
2001-11-14T23:59:59.000Z
in the exchange ~x!- only limit. In the latter approach @1#, theTime-dependent density-functional theor Study of multiphoton processes and dynam of N2 in inten Xi Chu and Department of Chemistry, University of Kansas, and Kansas Ce ~Received 30 July 2001; pu We...-I CHU PHYSICAL REVIEW A 64 0634041sg 21su 22sg 22su 21pu 43sg 2 . According to the valence bond theory, this molecule has a triple bond formed with 3sg and 1pu electrons. The 3sg orbital is parallel to the internuclear axis and the two degen- erate 1pu...
Coupling MD Simulations and X-ray Absorption Spectroscopy to Study Ions in Solution
Marcos, E. Sanchez; Beret, E. C.; Martinez, J. M.; Pappalardo, R. R. [University of Seville, Dept. of Physical Chemistry (Spain); Ayala, R.; Munoz-Paez, A. [University of Seville, CSIC-ICMSE. Dept. of Inorganic Chemistry (Spain)
2007-11-29T23:59:59.000Z
The structure of ionic solutions is a key-point in understanding physicochemical properties of electrolyte solutions. Among the reduced number of experimental techniques which can supply direct information on the ion environment, X-ray Absorption techniques (XAS) have gained importance during the last decades although they are not free of difficulties associated to the data analysis leading to provide reliable structures. Computer simulations of ions in solution is a theoretical alternative to provide information on the solvation structure. Thus, the use of computational chemistry can increase the understanding of these systems although an accurate description of ionic solvation phenomena represents nowadays a significant challenge to theoretical chemistry. We present: (a) the assignment of features in the XANES spectrum to well defined structural motif in the ion environment, (b) MD-based evaluation of EXAFS parameters used in the fitting procedure to make easier the structural resolution, and (c) the use of the agreement between experimental and simulated XANES spectra to help in the choice of a given intermolecular potential for Computer Simulations. Chemical problems examined are: (a) the identification of the second hydration shell in dilute aqueous solutions of highly-charged cations, such as Cr{sup 3+}, Rh{sup 3+}, Ir{sup 3+}, (b) the invisibility by XAS of certain structures characterized by Computer Simulations but exhibiting high dynamical behavior and (c) the solvation of Br{sup -} in acetonitrile.
Spin dynamics simulation of electron spin relaxation in Ni{sup 2+}(aq)
Rantaharju, Jyrki, E-mail: jjrantaharju@gmail.com; Mareš, Ji?í, E-mail: jiri.mares@oulu.fi; Vaara, Juha, E-mail: juha.vaara@iki.fi [NMR Research Group, Department of Physics, University of Oulu, P.O. Box 3000, Oulu, FIN-90014 (Finland)
2014-07-07T23:59:59.000Z
The ability to quantitatively predict and analyze the rate of electron spin relaxation of open-shell systems is important for electron paramagnetic resonance and paramagnetic nuclear magnetic resonance spectroscopies. We present a combined molecular dynamics (MD), quantum chemistry (QC), and spin dynamics simulation method for calculating such spin relaxation rates. The method is based on the sampling of a MD trajectory by QC calculations, to produce instantaneous parameters of the spin Hamiltonian used, in turn, to numerically solve the Liouville-von Neumann equation for the time evolution of the spin density matrix. We demonstrate the approach by simulating the relaxation of electron spin in an aqueous solution of Ni{sup 2+} ion. The spin-lattice (T{sub 1}) and spin-spin (T{sub 2}) relaxation rates are extracted directly from the simulations of the time dependence of the longitudinal and transverse magnetization, respectively. Good agreement with the available, indirectly obtained experimental data is obtained by our method.
Andrea E. Reid, M.D., M.P.H. INFORMATION
Goodrich, Lisa V.
to practice State: District of Columbia License No: MD038392 Initial Date: 01/01/2011 Renewal/Expiration Date Providence, RI 02912 9/1980-6/1984 ScB with Honors, Psychology Medical Education: Harvard Medical School 25
Boutaba, Raouf
, Sheikh Iqbal Ahamed, Md. Mostofa Akbar Department of Computer Science and Engineering, Bangladesh.com, sheikh.ahamed@mu.edu, mostofa@cse.buet.ac.bd Abstract. Health monitoring is repeatedly mentioned as one
Vehicle Technologies Office Merit Review 2014: Cummins MD & HD Accessory Hybridization CRADA
Broader source: Energy.gov [DOE]
Presentation given by Oak Ridge National Laboratory at 2014 DOE Hydrogen and Fuel Cells Program and Vehicle Technologies Office Annual Merit Review and Peer Evaluation Meeting about Cummins MD &...
E-Print Network 3.0 - amory codman md Sample Search Results
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
proud. During... , Emergency Surgery, and Surgical Critical Care (TESSCC), led by George P. Velmahos, MD, PhD, MSEd. George... is a skilled and committed teacher who has recruited...
Mapping molecular dynamics computations to hypercubes
Lakamsani, Vamsee Krishna
1993-01-01T23:59:59.000Z
December 1993 Major Subject: ('omputer Science MAPPING MOLECULAR DYNAMICS COMPUTATIONS TO HYPERCUBES A Thesis by VAMSEE IvRISHNA LAIvAMSANI Submitted to Texas AX. 'M University in partial fnlfillment of the requirements for the degree of lv... for systematic modeling, mapping and perfornianrc analysis of a Grand Challenge application problein in computational biology called Moleru- lar Dynamics S&tnufat&un uj Proteins Molecular Dynamics (MD) is an important techn&que used m computational...
Phenomenological Relativistic Energy Density Functionals
Lalazissis, G. A.; Kartzikos, S. [Physics Department, Aristotle University of Thessaloniki (Greece); Niksic, T.; Paar, N.; Vretenar, D. [Physics Department, University of Zagreb (Croatia); Ring, P. [Physics Department, TU Muenchen, Garching (Germany)
2009-08-26T23:59:59.000Z
The framework of relativistic nuclear energy density functionals is applied to the description of a variety of nuclear structure phenomena, not only in spherical and deformed nuclei along the valley of beta-stability, but also in exotic systems with extreme isospin values and close to the particle drip-lines. Dynamical aspects of exotic nuclear structure is explored using the fully consistent quasiparticle random-phase approximation based on the relativistic Hartree-Bogoliubov model. Recent applications of energy density functionals with explicit density dependence of the meson-nucleon couplings are presented.
Krishtal, Alisa; Genova, Alessandro; Pavanello, Michele
2015-01-01T23:59:59.000Z
Subsystem Density-Functional Theory (DFT) is an emerging technique for calculating the electronic structure of complex molecular and condensed phase systems. In this topical review, we focus on some recent advances in this field related to the computation of condensed phase systems, their excited states, and the evaluation of many-body interactions between the subsystems. As subsystem DFT is in principle an exact theory, any advance in this field can have a dual role. One is the possible applicability of a resulting method in practical calculations. The other is the possibility of shedding light on some quantum-mechanical phenomenon which is more easily treated by subdividing a supersystem into subsystems. An example of the latter is many-body interactions. In the discussion, we present some recent work from our research group as well as some new results, casting them in the current state-of-the-art in this review as comprehensively as possible.
Masson, Jean-Baptiste; Salvatico, Charlotte; Renner, Marianne; Specht, Christian G; Triller, Antoine; Dahan, Maxime
2015-01-01T23:59:59.000Z
Protein mobility is conventionally analyzed in terms of an effective diffusion. Yet, this description often fails to properly distinguish and evaluate the physical parameters (such as the membrane friction) and the biochemical interactions governing the motion. Here, we present a method combining high-density single-molecule imaging and statistical inference to separately map the diffusion and energy landscapes of membrane proteins across the cell surface at ~100 nm resolution (with acquisition of a few minutes). When applying these analytical tools to glycine neurotransmitter receptors (GlyRs) at inhibitory synapses, we find that gephyrin scaffolds act as shallow energy traps (~3 kBT) for GlyRs, with a depth modulated by the biochemical properties of the receptor-gephyrin interaction loop. In turn, the inferred maps can be used to simulate the dynamics of proteins in the membrane, from the level of individual receptors to that of the population, and thereby, to model the stochastic fluctuations of physiologi...
KuÂ?el, Petr
dynamics simulations to investigate ultrafast dynamics following electronic excitation of Coumarin 153 and dynamics, preferably at a molecular level of reso- lution. In particular, solvent relaxation following body of time-resolved spectro- scopic studies, as well as molecular dynamics MD simula- tions have been
Han, Kunwoo
2009-06-02T23:59:59.000Z
We apply a molecular dynamics (MD) simulation technique to complex molecules at interfaces. Partitioning of dendritic surfactants into clay gallery and Ab protein behavior near hydrated lipids are chosen for the purpose. Using a full atomistic model...
Shell Model Dynamics of HCl on the MgO(001) Surface Terrace Andreas Markmann,1
Markmann, Andreas
are then used to aid the analysis of MD calculations. After equilibrium dynamics, a sudden excitation of the OH of molecular dynamics using specially tailored laser fields. The reaction of hydrogen chloride moleculesShell Model Dynamics of HCl on the MgO(001) Surface Terrace Andreas Markmann,1 Jacob L. Gavartin,2
Tuscia, UniversitÃ Degli Studi Della
Dynamics of Different Hydrogen Classes in -lactoglobulin: A Quasielastic Neutron Scattering investigated by means of quasielastic neutron scattering. To discriminate the possibly different dynamical- thods,11-13 molecular dynamics (MD) simulations,14 X-ray crys- tallography,15 and neutron scattering.6
Southern California, University of
Molecular dynamics simulations of the nano-scale room-temperature oxidation of aluminum single Abstract The oxidation of aluminum single crystals is studied using molecular dynamics (MD) simulations with dynamic charge transfer between atoms. The simulations are performed on three aluminum low-index surfaces
Semiclassical analysis of quantum dynamics
Siyang Yang
2011-11-15T23:59:59.000Z
Simulating the molecular dynamics (MD) using classical or semi-classical trajectories provides important details for the understanding of many chemical reactions, protein folding, drug design, and solvation effects. MD simulations using trajectories have achieved great successes in the computer simulations of various systems, but it is difficult to incorporate quantum effects in a robust way. Therefore, improving quantum wavepacket dynamics and incorporating nonadiabatic transitions and quantum effects into classical and semi-classical molecular dynamics is critical as well as challenging. In this paper, we present a MD scheme in which a new set of equations of motion (EOM) are proposed to effectively propagate nuclear trajectories while conserving quantum mechanical energy which is critical for describing quantum effects like tunneling. The new quantum EOM is tested on a one-state one-dimensional and a two-state two-dimensional model nonadiabatic systems. The global quantum force experienced by each trajectory promotes energy redistribution among the bundle of trajectories, and thus helps the individual trajectory tunnel through the potential barrier higher than the energy of the trajectory itself. Construction of the new quantum force and EOM also provides a better way to treat the issue of back-reaction in mixed quantum-classical (MQC) methods, i.e. self-consistency between quantum degrees of freedom (DOF) and classical DOF.
Coupled displacive and orderdisorder dynamics in LiNbO3 by molecular-dynamics simulation
Gopalan, Venkatraman
.1063/1.1669063 Ferroelectric lithium niobate (LiNbO3) has emerged as an important material in surface acoustic wave devices1 the structure and properties of materials. Indeed, atomic-level simulations have been used previously-dynamics MD simulations described here we treat the Coulomb interactions using a direct summation method
Oberacker, V E
2015-01-01T23:59:59.000Z
In this manuscript we provide an outline of the numerical methods used in implementing the density constrained time-dependent Hartree-Fock (DC-TDHF) method and provide a few examples of its application to nuclear fusion. In this approach, dynamic microscopic calculations are carried out on a three-dimensional lattice and there are no adjustable parameters, the only input is the Skyrme effective NN interaction. After a review of the DC-TDHF theory and the numerical methods, we present results for heavy-ion potentials $V(R)$, coordinate-dependent mass parameters $M(R)$, and precompound excitation energies $E^{*}(R)$ for a variety of heavy-ion reactions. Using fusion barrier penetrabilities, we calculate total fusion cross sections $\\sigma(E_\\mathrm{c.m.})$ for reactions between both stable and neutron-rich nuclei. We also determine capture cross sections for hot fusion reactions leading to the formation of superheavy elements.
Nagle, John F.
HIV-1 Tat membrane interactions probed using X-ray and neutron scattering, CD spectroscopy and MD translocation, were provided by wide-angle X-ray scattering (WAXS) and neutron scattering. CD spectroscopy for Neutron Research, 100 Bureau Drive, Stop 6102, Gaithersburg, MD 20899, United States d CHESS, Cornell
says Michel Torbey, MD, medical director of OSU Medical Center's Neurovascular Stroke Center.
stroke says Michel Torbey, MD, medical director of OSU Medical Center's Neurovascular Stroke Center. "That means calling 911 as soon as you recognize signs in yourself or in someone nearby." When a stroke is brain,'" Dr. Torbey explains. `aMeriCa's best' stroke Care When a stroke patient arrives at The Ohio
CityBizList US Green Building Council -MD Celebrating Move to
CityBizList US Green Building Council - MD Celebrating Move to Hunt Valley Share Email this Article Baltimore County Executive Jim Smith will join the U.S. Green Building Council Maryland to celebrate Horst, Senior Vice President, U.S. Green Building Council. Horst has served as chair of USGBC's LEED
Vendor Location PHS Assurance# A&G Pharmaceutical, Inc. MD A4404-01
Bandettini, Peter A.
BioScience Labs MD A3467-01 Alpha Genesis, Inc. SC A3645-01 Antibody Research Corporation MO A4489. On the BPA Program website open the current 'BPA Commodity List' and use the 'animal services', 'biological materials' or 'blood/blood products' tabs to search for these vendors. If a vendor is listed, the purchaser
A coupled RISM/MD or MC simulation methodology for solvation free energies
Truong, Thanh N.
A coupled RISM/MD or MC simulation methodology for solvation free energies Holly Freedman, Thanh N September 2003 Published online: 24 October 2003 Abstract We propose a new computational methodology methods for determination of solvation free energies. We employ the RISM formulation of solvation free
Waterloo, University of
. Centrally controlled, company owned search engines, like Google, Yahoo and Bing, may not be sufficientDEWS: A Decentralized Engine for Web Search Reaz Ahmed, Rakibul Haque, Md. Faizul Bari, Raouf search engines, which is not healthy for our freedom in the Internet. A better solution is to enable
Ira Helfand, MD International Physicians for the Prevention of Nuclear War
Robock, Alan
Ira Helfand, MD International Physicians for the Prevention of Nuclear War Physicians for Social Responsibility NUCLEAR FAMINE: A BILLION PEOPLE AT RISK Global Impacts of Limited Nuclear War on Agriculture of studies have shown that a limited, regional nuclear war between India and Pakistan would cause significant
The National Institutes of Health Announces the 2014 NIH Regional Seminar in Baltimore, MD
Baker, Chris I.
The National Institutes of Health Announces the 2014 NIH Regional Seminar in Baltimore, MD Â· GRANT REGULATIONS AND POLICIES Â· AND MORE! Except for a visit to NIH, there is not another opportunity like the NIH, while spending 2 days learning the latest NIH grants policy and process information first-hand. Who
Hot Water DJ: Saving Energy by Pre-mixing Hot Water Md Anindya Prodhan
Whitehouse, Kamin
Hot Water DJ: Saving Energy by Pre-mixing Hot Water Md Anindya Prodhan Department of Computer University of Virginia whitehouse@virginia.edu Abstract After space heating and cooling, water heating consumption. Current water heating systems waste up to 20% of their energy due to poor insulation in pipes
Dynamic Evolution for Risk-Neutral Densities
2008-10-27T23:59:59.000Z
processes as well as actual price data for options on the S&P500 index. We also ..... for polynomials in real intervals, given by Bertsimas and Popescu [6]. To.
Kim, Chansoo, S.M. Massachusetts Institute of Technology
2008-01-01T23:59:59.000Z
A series of Molecular Dynamics (MD) simulations using the GROMACS® package has been performed in this thesis. It is used to mimic and simulate the hydration water in Lysozyme with three different hydration levels (h = 0.3, ...
Molecular dynamics simulations of the elastic properties of polymer/carbon nanotube composites
Elliott, James
Molecular dynamics simulations of the elastic properties of polymer/carbon nanotube composites Yue composite. However, improvements in properties are by no means guaranteed, and the results are often in the composite. In this paper, we present classical molecular dynamics (MD) simulations of model polymer
Mueser, Martin
Glassy dynamics, aging in mobility, and structural relaxation of strongly adsorbed polymer films of Western Ontario, London, Ontario N6A 5B7, Canada Abstract. A molecular dynamics simulation (MD. The model reproduces many experimentally observed features such as logarithmic aging of structural
Fayer, Michael D.
occur in the water structure and dynamics. At the same time, MD simulations have shown that the mostGeometry and Nanolength Scales versus Interface Interactions: Water Dynamics in AOT Lamellar Structures and Reverse Micelles David E. Moilanen, Emily E. Fenn, Daryl Wong, and M. D. Fayer* Department
Molecular Dynamics Simulation of Nucleation of SWNT from a Metal Particle on a Substrate
Maruyama, Shigeo
a transition metal cluster on a substrate is studied using classical molecular dynamics (MD) simulations between pure metal and metal-carbide. Graphite structure gradually precipitates from the edgeMolecular Dynamics Simulation of Nucleation of SWNT from a Metal Particle on a Substrate Yasushi
Heart Rate Dynamics Before Spontaneous Onset of Ventricular
Heart Rate Dynamics Before Spontaneous Onset of Ventricular Fibrillation in Patients With Healed V. Huikuri, MD The traditional methods of analyzing heart rate (HR) variability have failed myocardial infarction has been shown to be in- creased in patients with reduced heart rate (HR) vari- ability
Wismath, Stephen
A Linear Algorithm for Compact Box-Drawings of Trees Masud Hasan #3; , Md. Saidur Rahman y, Bangladesh. Email: m2hasan@hopper.math.uwaterloo.ca y Graduate School of Information Sciences, Tohoku Univer
Pair densities in density functional theory
Chen, Huajie
2015-01-01T23:59:59.000Z
The exact interaction energy of a many-electron system is determined by the electron pair density, which is not well-approximated in standard Kohn-Sham density functional models. Here we study the (complicated but well-defined) exact universal map from density to pair density. We show that many common functionals, including the most basic version of the LDA (Dirac exchange with no correlation contribution), arise from particular approximations of this map. We develop an algorithm to compute the map numerically, and apply it to one-parameter families {a*rho(a*x)} of one-dimensional homogeneous and inhomogeneous single-particle densities. We observe that the pair density develops remarkable multiscale patterns which strongly depend on both the particle number and the "width" 1/a of the single-particle density. The simulation results are confirmed by rigorous asymptotic results in the limiting regimes a>>1 and a<<1. For one-dimensional homogeneous systems, we show that the whole spectrum of patterns is rep...
Feblowitz, Joshua
2010-01-01T23:59:59.000Z
Clinical decision support is an emerging type of healthcare information technology that aims to actively guide doctors' decision-making processes. In its various forms, it can help physicians design treatment regimens, ...
National Nuclear Security Administration (NNSA)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr May Jun Jul(Summary) "ofEarlyEnergyDepartmentNational NuclearhasAdministration77NuclearSecurityAdministrator |Life0239. S .
Mapping densities in a noisy state space
Domenico Lippolis
2013-03-05T23:59:59.000Z
Weak noise smooths out fractals in a chaotic state space and introduces a maximum attainable resolution to its structure. The balance of noise and deterministic stretching/contraction in each neighborhood introduces local invariants of the dynamics that can be used to partition the state space. We study the local discrete-time evolution of a density in a two-dimensional hyperbolic state space, and use the asymptotic eigenfunctions for the noisy dynamics to formulate a new state space partition algorithm.
Yaws, C.L.; Yang, H.C.; Hopper, J.R.; Cawley, W.A. (Lamar Univ., Beaumont, TX (US))
1991-01-01T23:59:59.000Z
Saturated liquid densities for organic chemicals are given as functions of temperature using a modified Rackett equation.
Instabilities in the Nuclear Energy Density Functional
M. Kortelainen; T. Lesinski
2010-02-05T23:59:59.000Z
In the field of Energy Density Functionals (EDF) used in nuclear structure and dynamics, one of the unsolved issues is the stability of the functional. Numerical issues aside, some EDFs are unstable with respect to particular perturbations of the nuclear ground-state density. The aim of this contribution is to raise questions about the origin and nature of these instabilities, the techniques used to diagnose and prevent them, and the domain of density functions in which one should expect a nuclear EDF to be stable.
VA-MD-DC Hydrogen Education for Decision Makers | Department of Energy
Office of Energy Efficiency and Renewable Energy (EERE) Indexed Site
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative Fuels Data Center Home Page on Google Bookmark EERE: Alternative Fuels Data Center Home Page on Delicious RankCombustion |Energy Usage Â»of EnergyTheTwoVulnerabilities | Department of Energy 5:VA4-BVA-MD-DC
Density Perturbations for Running Cosmological Constant
Julio C. Fabris; Ilya L. Shapiro; Joan Sola
2007-01-26T23:59:59.000Z
The dynamics of density and metric perturbations is investigated for the previously developed model where the decay of the vacuum energy into matter (or vice versa) is due to the renormalization group (RG) running of the cosmological constant (CC) term. The evolution of the CC depends on the single parameter \
Steinhoff, Heinz-JÃ¼rgen
X- AND W-BAND EPR SPECTROSCOPY COMBINED WITH MOLECULAR DYNAMICS SIMULATIONS UNRAVEL THE STRUCTURE (EPR) spectroscopy is combined with molecular dynamics (MD) simulations to study the structure and thus the EPR spectral line shape contain direct information about the secondary and tertiary structure
Density-dependent covariant energy density functionals
Lalazissis, G. A. [Physics Department, Aristotle University of Thessaloniki, GR-54124 (Greece)
2012-10-20T23:59:59.000Z
Relativistic nuclear energy density functionals are applied to the description of a variety of nuclear structure phenomena at and away fromstability line. Isoscalar monopole, isovector dipole and isoscalar quadrupole giant resonances are calculated using fully self-consistent relativistic quasiparticle randomphase approximation, based on the relativistic Hartree-Bogoliubovmodel. The impact of pairing correlations on the fission barriers in heavy and superheavy nuclei is examined. The role of pion in constructing desnity functionals is also investigated.
Modeling ramp compression experiments using large-scale molecular dynamics simulation.
Mattsson, Thomas Kjell Rene; Desjarlais, Michael Paul; Grest, Gary Stephen; Templeton, Jeremy Alan; Thompson, Aidan Patrick; Jones, Reese E.; Zimmerman, Jonathan A.; Baskes, Michael I. (University of California, San Diego); Winey, J. Michael (Washington State University); Gupta, Yogendra Mohan (Washington State University); Lane, J. Matthew D.; Ditmire, Todd (University of Texas at Austin); Quevedo, Hernan J. (University of Texas at Austin)
2011-10-01T23:59:59.000Z
Molecular dynamics simulation (MD) is an invaluable tool for studying problems sensitive to atomscale physics such as structural transitions, discontinuous interfaces, non-equilibrium dynamics, and elastic-plastic deformation. In order to apply this method to modeling of ramp-compression experiments, several challenges must be overcome: accuracy of interatomic potentials, length- and time-scales, and extraction of continuum quantities. We have completed a 3 year LDRD project with the goal of developing molecular dynamics simulation capabilities for modeling the response of materials to ramp compression. The techniques we have developed fall in to three categories (i) molecular dynamics methods (ii) interatomic potentials (iii) calculation of continuum variables. Highlights include the development of an accurate interatomic potential describing shock-melting of Beryllium, a scaling technique for modeling slow ramp compression experiments using fast ramp MD simulations, and a technique for extracting plastic strain from MD simulations. All of these methods have been implemented in Sandia's LAMMPS MD code, ensuring their widespread availability to dynamic materials research at Sandia and elsewhere.
A study of QM/Langevin-MD simulation for oxygen-evolving center of photosystem II
Uchida, Waka; Kimura, Yoshiro; Wakabayashi, Masamitsu [Department of Biomolecular Engineering, Tokyo Institute of Technology, Nagatsuta, Midori-ku, Yokohama 226-8503 (Japan); Hatakeyama, Makoto; Ogata, Koji; Nakamura, Shinichiro [RIKEN Research Cluster for Innovation, Nakamura Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan); Yokojima, Satoshi [Tokyo University of Pharmacy and Life Sciences, 1432-1 Horinouchi, Hachioji, Tokyo 192-0392, Japan and RIKEN Research Cluster for Innovation, Nakamura Laboratory, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
2013-12-10T23:59:59.000Z
We have performed three QM/Langevin-MD simulations for oxygen-evolving complex (OEC) and surrounding residues, which are different configurations of the oxidation numbers on Mn atoms in the Mn{sub 4}O{sub 5}Ca cluster. By analyzing these trajectories, we have observed sensitivity of the change to the configuration of Mn oxidation state on O atoms of carboxyl on three amino acids, Glu354, Ala344, and Glu333. The distances from Mn to O atoms in residues contacting with the Mn{sub 4}O{sub 5}Ca cluster were analyzed for the three trajectories. We found the good correlation of the distances among the simulations. However, the distances with Glu354, Ala344, and Glu333 have not shown the correlation. These residues can be sensitive index of the changes of Mn oxidation numbers.
Russell, Lynn
Surface Tensions in NaCl-Water-Air Systems from MD Simulations Ranjit Bahadur, Lynn M. Russell, Ottawa, Ontario K1A 0R6, Canada ReceiVed: July 9, 2007; In Final Form: July 30, 2007 Surface tensions to the surface tension, while the energy-integral and test area methods provide direct estimates. At 1 atm
Reid, Nancy
Survival in Academy AwardWinning Actors and Actresses Donald A. Redelmeier, MD, and Sheldon M in status from winning an academy award is associated with long-term mortality among actors and actresses. Design: Retrospective cohort analysis. Setting: Academy of Motion Picture Arts and Sciences. Participants
Inkpen, Diana
Second Order Co-occurrence PMI for Determining the Semantic Similarity of Words Md. Aminul Islam for calculating the semantic similarity of two target words. Our method, called Second Order Co-occurrence PMI (SOC-PMI), uses Pointwise Mutual Information to sort lists of important neighbor words of the two
Madhyastha, Harsha V.
FRAppE: Detecting Malicious Facebook Applications Md Sazzadur Rahman, Ting-Kai Huang, Harsha V for the popularity and addictiveness of Facebook. Unfortu- nately, hackers have realized the potential of using apps and campaigns. In this paper, we ask the question: given a Facebook application, can we determine
Paris-Sud XI, UniversitÃ© de
The evaluation within the development and deployment of IMS LD-based didactic materials: The MD2 in the didactic materials creation since it allows developers to check if the features of created material satisfy]. They have been applied to asses IMS LD based didactic material in conjunction with the experience provided
Transient Analysis of a Preemptive Resume M/D/1/2/2 through Petri Nets \\Lambda
Telek, MiklÃ³s
Transient Analysis of a Preemptive Resume M/D/1/2/2 through Petri Nets \\Lambda Andrea Bobbio a semantical generalization of the DSPNs by including preemptive mechanisms of resume type. This generalization different preemptive resume policies. Key words: Markov regenerative processes, Stochastic Petri Nets
Wang, Wei
to the construction of van der Waals interaction energy profiles for each ligand as well as for wild-type and mutant Dynamics, Free Energy Calculations, and Sequence Analysis Wei Wang, Wendell A. Lim,, Araz Jakalian,§,# Jian the interactions between Sem-5 and its ligands using molecular dynamics (MD), free energy calculations
Van Zee, John W.
Determination of the Dynamic Characteristics in the CO Transient Process in a PEM Fuel Cell Woo Road, Elkton, MD 21922-1488 Key words: PEM Fuel Cell, CO transient, Time constant Prepared publications #12;1 Determination of the Dynamic Characteristics in the CO Transient Process in a PEM Fuel Cell
Goddard III, William A.
Dynamics (MD) techniques to simulate glass structures has become a valuable tool for gaining insight1 9/28/98 9:58:58 am, Journal of Non-Crystalline Solids MOLECULAR DYNAMICS SIMULATION OF VITREOUS SILICA STRUCTURES Norman T. Huff*, Owens Corning Science and Technology Center, 2790 Columbus Road
X-ray Diffraction and Molecular Dynamics Study of Medium-range Order in Ambient and Hot Water
Congcong Huang; K. T. Wikfeldt; D. Nordlund; U. Bergmann; T. McQueen; J. Sellberg; L. G. M. Pettersson; A. Nilsson
2011-07-24T23:59:59.000Z
We have developed x-ray diffraction measurements with high energy-resolution and accuracy to study water structure at three different temperatures (7, 25 and 66 C) under normal pressure. Using a spherically curved Ge crystal an energy resolution better than 15 eV has been achieved which eliminates influence from Compton scattering. The high quality of the data allows a precise oxygen-oxygen pair correlation function (PCF) to be directly derived from the Fourier transform of the experimental data resolving shell structure out to ~12 {\\AA}, i.e. 5 hydration shells. Large-scale molecular dynamics (MD) simulations using the TIP4P/2005 force-field reproduce excellently the experimental shell-structure in the range 4-12 {\\AA} although less agreement is seen for the first peak in the PCF. The Local Structure Index [J. Chem. Phys. 104, 7671 (1996)] identifies a tetrahedral minority giving the intermediate-range oscillations in the PCF and a disordered majority providing a more featureless background in this range. The current study supports the proposal that the structure of liquid water, even at high temperatures, can be described in terms of a two-state fluctuation model involving local structures related to the high-density and low-density forms of liquid water postulated in the liquid-liquid phase transition hypothesis.
Density Matrix Topological Insulators
A. Rivas; O. Viyuela; M. A. Martin-Delgado
2013-10-31T23:59:59.000Z
Thermal noise can destroy topological insulators (TI). However we demonstrate how TIs can be made stable in dissipative systems. To that aim, we introduce the notion of band Liouvillian as the dissipative counterpart of band Hamiltonian, and show a method to evaluate the topological order of its steady state. This is based on a generalization of the Chern number valid for general mixed states (referred to as density matrix Chern value), which witnesses topological order in a system coupled to external noise. Additionally, we study its relation with the electrical conductivity at finite temperature, which is not a topological property. Nonetheless, the density matrix Chern value represents the part of the conductivity which is topological due to the presence of quantum mixed edge states at finite temperature. To make our formalism concrete, we apply these concepts to the two-dimensional Haldane model in the presence of thermal dissipation, but our results hold for arbitrary dimensions and density matrices.
Density Functional Theory for Superconductors
Gross, E.K.U.
Density Functional Theory for Superconductors LATHIOTAKIS, A. MARQUES, 1,2,3 LU DERS, L. FAST, 2004 words: theory superconductors; density functional theory; critical temperature; exchange matter physics theoretical chemistry is density functional theory (DFT). foundations were established mid
Siebenmorgen, Ralf
Ref. ESO doc number File name Document title Author MD03 E-PLA-MET-503-0003 e-pla-met-503 S. Hippler MD16 E-PLA-MET-503-0016 e-pla-met-503-0016-ait_plan.pdf AIT Plan F. Molster MD17 E
Constraints on the density dependence of the symmetry energy
M. B. Tsang; Yingxun Zhang; P. Danielewicz; M. Famiano; Zhuxia Li; W. G. Lynch; A. W. Steiner
2008-11-19T23:59:59.000Z
Collisions involving 112Sn and 124Sn nuclei have been simulated with the improved Quantum Molecular Dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at sub-normal density are obtained. Results from present work are compared to constraints put forward in other recent analysis.
Constraints on the Density Dependence of the Symmetry Energy
Tsang, M. B.; Danielewicz, P.; Lynch, W. G.; Steiner, A. W. [Joint Institute of Nuclear Astrophysics and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); Physics and Astronomy Department, Michigan State University, East Lansing, Michigan 48824 (United States); Zhang Yingxun [Joint Institute of Nuclear Astrophysics and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, Michigan 48824 (United States); China Institute of Atomic Energy, P.O. Box 275 (18), Beijing 102413 (China); Famiano, M. [Physics Department, Western Michigan University, Kalamazoo, Michigan 49008 (United States); Li, Zhuxia [China Institute of Atomic Energy, P.O. Box 275 (18), Beijing 102413 (China)
2009-03-27T23:59:59.000Z
Collisions involving {sup 112}Sn and {sup 124}Sn nuclei have been simulated with the improved quantum molecular dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at subnormal density are obtained. The results from the present work are compared to constraints put forward in other recent analyses.
Constraints on the density dependence of the symmetry energy
Tsang, M B; Danielewicz, P; Famiano, M; Li, Zhuxia; Lynch, W G; Steiner, A W
2008-01-01T23:59:59.000Z
Collisions involving 112Sn and 124Sn nuclei have been simulated with the improved Quantum Molecular Dynamics transport model. The results of the calculations reproduce isospin diffusion data from two different observables and the ratios of neutron and proton spectra. By comparing these data to calculations performed over a range of symmetry energies at saturation density and different representations of the density dependence of the symmetry energy, constraints on the density dependence of the symmetry energy at sub-normal density are obtained. Results from present work are compared to constraints put forward in other recent analysis.
Molecular dynamics simulation of chains mobility in polyethylene crystal
V. I. Sultanov; V. V. Atrazhev; D. V. Dmitriev; S. F. Burlatsky
2014-01-17T23:59:59.000Z
The mobility of polymer chains in perfect polyethylene (PE) crystal was calculated as a function of temperature and chain length through Molecular dynamics (MD) in united atom approximation. The results demonstrate that the chain mobility drastically increases in the vicinity of the phase transition from the orthorhombic to quasi-hexagonal phase. In the quasi-hexagonal phase, the chain mobility is almost independent on temperature and inversely proportional to the chain length.
Multiple density layered insulator
Alger, T.W.
1994-09-06T23:59:59.000Z
A multiple density layered insulator for use with a laser is disclosed which provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation. 4 figs.
Multiple density layered insulator
Alger, Terry W. (Tracy, CA)
1994-01-01T23:59:59.000Z
A multiple density layered insulator for use with a laser is disclosed wh provides at least two different insulation materials for a laser discharge tube, where the two insulation materials have different thermoconductivities. The multiple layer insulation materials provide for improved thermoconductivity capability for improved laser operation.
Vranjes, J
2015-01-01T23:59:59.000Z
Inhomogeneous plasmas and fluids contain energy stored in inhomogeneity and they naturally tend to relax into lower energy states by developing instabilities or by diffusion. But the actual amount of energy in such inhomogeneities has remained unknown. In the present work the amount of energy stored in a density gradient is calculated for several specific density profiles in a cylindric configuration. This is of practical importance for drift wave instability in various plasmas, and in particular in its application in models dealing with the heating of solar corona because the instability is accompanied with stochastic heating, so the energy contained in inhomogeneity is effectively transformed into heat. It is shown that even for a rather moderate increase of the density at the axis in magnetic structures in the corona by a factor 1.5 or 3, the amount of excess energy per unit volume stored in such a density gradient becomes several orders of magnitude greater than the amount of total energy losses per unit ...
A. Iakovlev; D. Bedrov; M. Müller
2014-12-08T23:59:59.000Z
The surface properties of liquid mercury (Hg) at a temperature of 293 K are investigated by classical Molecular Dynamics simulation using density-independent (DI) and density-dependent (DD) force fields. The latter force fields were introduced to improve the description of surface properties. Both force fields yield lower values of the surface tension in comparison to experimental data. Moreover, the density-dependent force field results in an anomalous thermodynamic behavior. These findings are rationalized by liquid-state theory. An optimized, density-independent force field is proposed that yields a higher surface tension and, at the same time, provides an accurate description of the liquid-vapor coexistence.
Orbital-optimized density cumulant functional theory
Sokolov, Alexander Yu., E-mail: asokolov@uga.edu; Schaefer, Henry F. [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)] [Center for Computational Quantum Chemistry, University of Georgia, Athens, Georgia 30602 (United States)
2013-11-28T23:59:59.000Z
In density cumulant functional theory (DCFT) the electronic energy is evaluated from the one-particle density matrix and two-particle density cumulant, circumventing the computation of the wavefunction. To achieve this, the one-particle density matrix is decomposed exactly into the mean-field (idempotent) and correlation components. While the latter can be entirely derived from the density cumulant, the former must be obtained by choosing a specific set of orbitals. In the original DCFT formulation [W. Kutzelnigg, J. Chem. Phys. 125, 171101 (2006)] the orbitals were determined by diagonalizing the effective Fock operator, which introduces partial orbital relaxation. Here we present a new orbital-optimized formulation of DCFT where the energy is variationally minimized with respect to orbital rotations. This introduces important energy contributions and significantly improves the description of the dynamic correlation. In addition, it greatly simplifies the computation of analytic gradients, for which expressions are also presented. We offer a perturbative analysis of the new orbital stationarity conditions and benchmark their performance for a variety of chemical systems.
Hulet, E.K.; Wild, J.F.; Lougheed, R.W.; Baisden, P.A.; Dougan, R.J.; Mustafa, M.G.
1980-10-01T23:59:59.000Z
The fragment energies of about 725 coincidence events have now been observed in the spontaneous fission (SF) decay of 105-min /sup 259/Md since its discovery in 1977. The fission of /sup 259/Md is characterized by a symmetric mass distribution, similar to those of /sup 258/Fm and /sup 259/Fm, but with a broad total kinetic energy (anti TKE) distribution which peaks at about 195 MeV, in contrast to those of /sup 258/Fm and /sup 259/Fm, for which the anti TKE is about 240 MeV. This kinetic energy deficit, approx. 40 MeV, has been postulated to be due to the emission of hydrogen-like particles by /sup 259/Md at the scission point in a large fraction of the fissions, leaving the residual fissioning nucleus with 100 protons. The residual nucleus would then be able to divide into two ultrastable tin-like fission fragments, but with less kinetic energy than that observed in the SF of /sup 258/Fm and /sup 259/Fm, because of binding-energy losses and a reduction in the Coulomb repulsion of the major fragments. To test this hypothesis, counter-telescope experiments aimed at detecting and identifying these light particles were performed. In 439 SF events 3 + 3 protons of the appropriate energy were observed, too few to account for the kinetic energy deficit in the fission of /sup 259/Md. There seems to be no explanation for this problem within the framework of current fission theory. These results are discussed along with preliminary measurements of light-particle emission in the SF of /sup 256/Fm. 5 figures.
Gedanken densities and exact constraints in density functional theory
Perdew, John P. [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States) [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Department of Chemistry, Temple University, Philadelphia, Pennsylvania 19122 (United States); Ruzsinszky, Adrienn; Sun, Jianwei [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States)] [Department of Physics, Temple University, Philadelphia, Pennsylvania 19122 (United States); Burke, Kieron [Department of Chemistry and Department of Physics, University of California, Irvine, California 92697 (United States)] [Department of Chemistry and Department of Physics, University of California, Irvine, California 92697 (United States)
2014-05-14T23:59:59.000Z
Approximations to the exact density functional for the exchange-correlation energy of a many-electron ground state can be constructed by satisfying constraints that are universal, i.e., valid for all electron densities. Gedanken densities are designed for the purpose of this construction, but need not be realistic. The uniform electron gas is an old gedanken density. Here, we propose a spherical two-electron gedanken density in which the dimensionless density gradient can be an arbitrary positive constant wherever the density is non-zero. The Lieb-Oxford lower bound on the exchange energy can be satisfied within a generalized gradient approximation (GGA) by bounding its enhancement factor or simplest GGA exchange-energy density. This enhancement-factor bound is well known to be sufficient, but our gedanken density shows that it is also necessary. The conventional exact exchange-energy density satisfies no such local bound, but energy densities are not unique, and the simplest GGA exchange-energy density is not an approximation to it. We further derive a strongly and optimally tightened bound on the exchange enhancement factor of a two-electron density, which is satisfied by the local density approximation but is violated by all published GGA's or meta-GGA’s. Finally, some consequences of the non-uniform density-scaling behavior for the asymptotics of the exchange enhancement factor of a GGA or meta-GGA are given.
A Density Functional Theory Study of Hydrogen Adsorption in MOF-5 Tim Mueller and Gerbrand Ceder*
Ceder, Gerbrand
A Density Functional Theory Study of Hydrogen Adsorption in MOF-5 Tim Mueller and Gerbrand Ceder initio molecular dynamics in the generalized gradient approximation to density functional theory to store hydrogen with sufficient gravimetric and volumetric densities to be economi- cally practical
Scaled Density Functional Theory Correlation Functionals Mohammed M. Ghouri,a
Ramachandran, Bala (Ramu)
Scaled Density Functional Theory Correlation Functionals Mohammed M. Ghouri,a Saurabh Singh,a and B by Density Functional Theory (DFT)2 correlation functionals without significant deterioration that a simple one parameter scaling of the dynamical correlation energy estimated by the Density Functional
Oakleaf, Megan
2009-01-01T23:59:59.000Z
by The Johns Hopkins University Press, Baltimore, MD 21218. INFORMATION STANDARDS Guiding Questions the information literacy assessments that best fit their needs. #12;Guiding Questions forAssessing Information
Zhigilei, Leonid V.
Department, University of Uppsala, Box 530, SE-751 21 Uppsala, Sweden 2Lawrence Livermore National Laboratory, Livermore, California 94550, USA 3National Centre for Laser Applications, Galway, Ireland 4Department at the National Ignition Facility NIF . Molecular dynamics MD simulations have been success- fully employed
Probing the density dependence of symmetry energy at subsaturation density with HICs
Zhang, Yingxun; Li, Zhuxia; Danielewicz, P; Lynch, W G; Lu, Xiaohua
2009-01-01T23:59:59.000Z
The reaction mechanism of the central collisions and peripheral collisions for $^{112,124}Sn+^{112,124}Sn$ at $E/A=50MeV$ is investigated within the framework of the Improved Quantum Molecular Dynamics model. The results show that multifragmentation process is an important mechanism at this energy region, and the influence of the cluster emission on the double n/p ratios and the isospin transport ratio are important. Furthermore, three observables, double n/p ratios, isospin diffusion and the rapidity distribution of the ratio $R_{7}$ for $^{112,124}Sn+^{112,124}Sn$ at E/A=50MeV are analyzed with the Improved Quantum Molecular Dynamics model. The results show that these three observables are sensitive to the density dependence of the symmetry energy. By comparing the calculation results to the data, the consistent constraint on the density dependence of the symmetry energy from these three observables is obtained.
Probing the density dependence of symmetry energy at subsaturation density with HICs
Yingxun Zhang; M. B. Tsang; Zhuxia Li; P. Danielewicz; W. G. Lynch; Xiaohua Lu
2009-11-09T23:59:59.000Z
The reaction mechanism of the central collisions and peripheral collisions for $^{112,124}Sn+^{112,124}Sn$ at $E/A=50MeV$ is investigated within the framework of the Improved Quantum Molecular Dynamics model. The results show that multifragmentation process is an important mechanism at this energy region, and the influence of the cluster emission on the double n/p ratios and the isospin transport ratio are important. Furthermore, three observables, double n/p ratios, isospin diffusion and the rapidity distribution of the ratio $R_{7}$ for $^{112,124}Sn+^{112,124}Sn$ at E/A=50MeV are analyzed with the Improved Quantum Molecular Dynamics model. The results show that these three observables are sensitive to the density dependence of the symmetry energy. By comparing the calculation results to the data, the consistent constraint on the density dependence of the symmetry energy from these three observables is obtained.
High Energy Density Capacitors
None
2010-07-01T23:59:59.000Z
BEEST Project: Recapping is developing a capacitor that could rival the energy storage potential and price of today’s best EV batteries. When power is needed, the capacitor rapidly releases its stored energy, similar to lightning being discharged from a cloud. Capacitors are an ideal substitute for batteries if their energy storage capacity can be improved. Recapping is addressing storage capacity by experimenting with the material that separates the positive and negative electrodes of its capacitors. These separators could significantly improve the energy density of electrochemical devices.
Ayala, A.L. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica][Pelotas Univ., RS (Brazil). Inst. de Fisica e Matematica; Ducati, M.B.G. [Rio Grande do Sul Univ., Porto Alegre, RS (Brazil). Inst. de Fisica; Levin, E.M. [Fermi National Accelerator Lab., Batavia, IL (United States)][Nuclear Physics Inst., St. Petersburg (Russian Federation)
1996-10-01T23:59:59.000Z
In this talk we present our detailed study (theory and numbers) on the shadowing corrections to the gluon structure functions for nuclei. Starting from rather controversial information on the nucleon structure function which is originated by the recent HERA data, we develop the Glauber approach for the gluon density in a nucleus based on Mueller formula and estimate the value of the shadowing corrections in this case. Then we calculate the first corrections to the Glauber approach and show that these corrections are big. Based on this practical observation we suggest the new evolution equation which takes into account the shadowing corrections and solve it. We hope to convince you that the new evolution equation gives a good theoretical tool to treat the shadowing corrections for the gluons density in a nucleus and, therefore, it is able to provide the theoretically reliable initial conditions for the time evolution of the nucleus-nucleus cascade. The initial conditions should be fixed both theoretically and phenomenologically before to attack such complicated problems as the mixture of hard and soft processes in nucleus-nucleus interactions at high energy or the theoretically reliable approach to hadron or/and parton cascades for high energy nucleus-nucleus interaction. 35 refs., 24 figs., 1 tab.
Trillion-atom molecular dynamics becomes a reality
Kadau, Kai [Los Alamos National Laboratory; Germann, Timothy C [Los Alamos National Laboratory
2008-01-01T23:59:59.000Z
By utilizing the molecular dynamics code SPaSM on Livermore's BlueGene/L architecture, consisting of 212 992 IBM PowerPC440 700 MHz processors, a molecular dynamics simulation was run with one trillion atoms. To demonstrate the practicality and future potential of such ultra large-scale simulations, the onset of the mechanical shear instability occurring in a system of Lennard-Jones particles arranged in a simple cubic lattice was simulated. The evolution of the instability was analyzed on-the-fly using the in-house developed massively parallel graphical object-rendering code MD{_}render.
Low density microcellular foams
LeMay, James D. (Castro Valley, CA)
1992-01-01T23:59:59.000Z
Disclosed is a process of producing microcellular from which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.
Low density microcellular foams
LeMay, J.D.
1991-11-19T23:59:59.000Z
Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 [mu]m is produced. Also disclosed are the foams produced by the process. 8 figures.
Low density microcellular foams
LeMay, James D. (Castro Valley, CA)
1991-01-01T23:59:59.000Z
Disclosed is a process of producing microcellular foam which comprises the steps of: (a) selecting a multifunctional epoxy oligomer resin; (b) mixing said epoxy resin with a non-reactive diluent to form a resin-diluent mixture; (c) forming a diluent containing cross-linked epoxy gel from said resin-diluent mixture; (d) replacing said diluent with a solvent therefore; (e) replacing said solvent with liquid carbon dioxide; and (f) vaporizing off said liquid carbon dioxide under supercritical conditions, whereby a foam having a density in the range of 35-150 mg/cc and cell diameters less than about 1 .mu.m is produced. Also disclosed are the foams produced by the process.
Nuclear Energy Density Optimization
M. Kortelainen; T. Lesinski; J. Moré; W. Nazarewicz; J. Sarich; N. Schunck; M. V. Stoitsov; S. Wild
2010-05-27T23:59:59.000Z
We carry out state-of-the-art optimization of a nuclear energy density of Skyrme type in the framework of the Hartree-Fock-Bogoliubov (HFB) theory. The particle-hole and particle-particle channels are optimized simultaneously, and the experimental data set includes both spherical and deformed nuclei. The new model-based, derivative-free optimization algorithm used in this work has been found to be significantly better than standard optimization methods in terms of reliability, speed, accuracy, and precision. The resulting parameter set UNEDFpre results in good agreement with experimental masses, radii, and deformations and seems to be free of finite-size instabilities. An estimate of the reliability of the obtained parameterization is given, based on standard statistical methods. We discuss new physics insights offered by the advanced covariance analysis.
Density Functional Theory for Superconductors
Gross, E.K.U.
Density Functional Theory for Superconductors N. N. LATHIOTAKIS,1,2 M. A. L. MARQUES,1,2,3 M. LU; density functional theory; critical temperature; exchange and correlation; phonon and theoretical chemistry is density functional theory (DFT). Its foundations were established in the mid-1960s
Molecular Dynamics Simulations of Solutions at Constant Chemical Potential
Perego, Claudio; Parrinello, Michele
2015-01-01T23:59:59.000Z
Molecular Dynamics studies of chemical processes in solution are of great value in a wide spectrum of applications, that range from nano-technology to pharmaceutical chemistry. However, these calculations are affected by severe finite-size effects, such as the solution being depleted as the chemical process proceeds, that influence the outcome of the simulations. To overcome these limitations, one must allow the system to exchange molecules with a macroscopic reservoir, thus sampling a Grand-Canonical ensemble. Despite the fact that different remedies have been proposed, this still represents a key challenge in molecular simulations. In the present work we propose the C$\\mu$MD method, which introduces an external force that controls the environment of the chemical process of interest. This external force, drawing molecules from a finite reservoir, maintains the chemical potential constant in the region where the process takes place. We have applied the C$\\mu$MD method to the paradigmatic case of urea crystall...
Observation of a Rotational Band in the Odd-Z Transfermium Nucleus {sub 101}{sup 251}Md
Chatillon, A.; Theisen, Ch.; Bouchez, E.; Clement, E.; Goergen, A.; Huerstel, A.; Korten, W.; Le Coz, Y.; Wilson, J. N. [CEA-SACLAY, DSM/DAPNIA/SPhN, F-91191 Gif-sur-Yvette Cedex (France); Butler, P. A.; Herzberg, R.-D.; Jones, G. D. [Oliver Lodge Laboratory, University of Liverpool, L697ZE (United Kingdom); Dorvaux, O.; Gall, B. J. P.; Khalfallah, F.; Rousseau, M. [Institut Pluridisciplinaire Hubert Curien, F-67037 Strasbourg (France); Eeckhaudt, S.; Grahn, T.; Greenlees, P. T.; Jones, P. [Department of Physics, University of Jyvaeskylae, Fin-40500 (Finland)] (and others)
2007-03-30T23:59:59.000Z
A rotational band has been unambiguously observed in an odd-proton transfermium nucleus for the first time. An in-beam {gamma}-ray spectroscopic study of {sub 101}{sup 251}Md has been performed using the {gamma}-ray array JUROGAM combined with the gas-filled separator RITU and the focal plane device GREAT. The experimental results, compared to Hartree-Fock-Bogolyubov calculations, lead to the interpretation that the rotational band is built on the [521]1/2{sup -} Nilsson state.
Canonical density matrix perturbation theory
Niklasson, Anders M N; Rubensson, Emanuel H; Rudberg, Elias
2015-01-01T23:59:59.000Z
Density matrix perturbation theory [Niklasson and Challacombe, Phys. Rev. Lett. 92, 193001 (2004)] is generalized to canonical (NVT) free energy ensembles in tight-binding, Hartree-Fock or Kohn-Sham density functional theory. The canonical density matrix perturbation theory can be used to calculate temperature dependent response properties from the coupled perturbed self-consistent field equations as in density functional perturbation theory. The method is well suited to take advantage of sparse matrix algebra to achieve linear scaling complexity in the computational cost as a function of system size for sufficiently large non-metallic materials and metals at high temperatures.
Generation of Gaussian Density Fields
Hugo Martel
2005-07-15T23:59:59.000Z
This document describes analytical and numerical techniques for the generation of Gaussian density fields, which represent cosmological density perturbations. The mathematical techniques involved in the generation of density harmonics in k-space, the filtering of the density fields, and the normalization of the power spectrum to the measured temperature fluctuations of the Cosmic Microwave Background, are presented in details. These techniques are well-known amongst experts, but the current literature lacks a formal description. I hope that this technical report will prove useful to new researchers moving into this field, sparing them the task of reinventing the wheel.
Dynamics of a Submesoscale Surface Ocean Density Front
Abramczyk, Marshall
2012-01-01T23:59:59.000Z
pushbroom 450 cross-track FLIR SC6000 1.0-5.0 (Mid wave)work by Jeroen Molemaker. A FLIR A325 long wave IR (7.5-13of clouds or vessels. The FLIR A325 is accurate to ± 2% of
Dynamics of a Submesoscale Surface Ocean Density Front
Abramczyk, Marshall
2012-01-01T23:59:59.000Z
green [Jeroen Molemaker, personal communication]. ..in green [Jeroen Molemaker, personal communication]. Figure
SciTech Connect: Chiral dynamics and peripheral transverse densities
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administrationcontroller systems controllerAdditiveBetatron Radiation fromTop FB Asymmetry and
Density Functional Theory (DFT) Simulated Annealing (SA)
. . . . . . . . 9 2009 #12;! " # $ % & - " # $ %' ! " # # $ % & # ( # " ) Density Functional Theory) % Lattice-Boltzmann (LBM) #12;! " # $ % & - " # $ %' ! " # # $ % & # ( # " ) Density Functional Theory (DFT;! " # $ % & - " # $ %' ! " # # $ % & # ( # " ) Density Functional Theory (DFT) Simulated Annealing (SA) Monte Carlo &$ ' ' (GCMC
Condensation ---conditional density propagation for visual Michael Isard and Andrew Blake,
Condensation --- conditional density propagation for visual tracking Michael Isard and Andrew Blake simultaneous alternative hypotheses. The Condensation algorithm uses ``factored sampling'', previously applied by a randomly generated set. Condensation uses learned dynamical models, together with visual observations
Charge transport, configuration interaction and Rydberg states under density functional theory
Cheng, Chiao-Lun
2008-01-01T23:59:59.000Z
Density functional theory (DFT) is a computationally efficient formalism for studying electronic structure and dynamics. In this work, we develop DFT-based excited-state methods to study electron transport, Rydberg excited ...
Trajectory mixture density networks with multiple mixtures for acoustic-articulatory inversion
Richmond, Korin
We have previously proposed a trajectory model which is based on a mixture density network (MDN) trained with target variables augmented with dynamic features together with an algorithm for estimating maximum likelihood trajectories which respects...
Direct experimental determination of spectral densities of molecular complexes
Pachón, Leonardo A. [Grupo de Física Atómica y Molecular, Instituto de Física, Facultad de Ciencias Exactas y Naturales, Universidad de Antioquia UdeA, Calle 70 No. 52-21, Medellín (Colombia); Chemical Physics Theory Group, Department of Chemistry and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6 (Canada); Brumer, Paul [Chemical Physics Theory Group, Department of Chemistry and Center for Quantum Information and Quantum Control, University of Toronto, Toronto, Ontario M5S 3H6 (Canada)
2014-11-07T23:59:59.000Z
Determining the spectral density of a molecular system immersed in a proteomic scaffold and in contact to a solvent is a fundamental challenge in the coarse-grained description of, e.g., electron and energy transfer dynamics. Once the spectral density is characterized, all the time scales are captured and no artificial separation between fast and slow processes need to be invoked. Based on the fluorescence Stokes shift function, we utilize a simple and robust strategy to extract the spectral density of a number of molecular complexes from available experimental data. Specifically, we show that experimental data for dye molecules in several solvents, amino acid proteins in water, and some photochemical systems (e.g., rhodopsin and green fluorescence proteins), are well described by a three-parameter family of sub-Ohmic spectral densities that are characterized by a fast initial Gaussian-like decay followed by a slow algebraic-like decay rate at long times.
Why are Fluid Densities So Low in Carbon Nanotubes?
Gerald J. Wang; Nicolas G. Hadjiconstantinou
2014-09-27T23:59:59.000Z
The equilibrium density of fluids under nanoconfinement can differ substantially from their bulk density. Using a mean-field approach to describe the energetic landscape near the carbon nanotube (CNT) wall, we obtain analytical results describing the lengthscales associated with the layering observed at the fluid-CNT interface. When combined with molecular simulation results for the fluid density in the layered region, this approach allows us to derive a closed-form prediction for the overall equilibrium fluid density as a function of the CNT radius that is in excellent agreement with molecular dynamics simulations. We also show how aspects of this theory can be extended to describe water confined within CNTs and find good agreement with results from the literature.
Direct Experimental Determination of Spectral Densities of Molecular Complexes
Leonardo A. Pachon; Paul Brumer
2014-10-15T23:59:59.000Z
Determining the spectral density of a molecular system immersed in a proteomic scaffold and in contact to a solvent is a fundamental challenge in the coarse-grained description of, e.g., electron and energy transfer dynamics. Once the spectral density is characterized, all the time scales are captured and no artificial separation between fast and slow processes need be invoked. Based on the fluorescence Stokes shift function, we utilize a simple and robust strategy to extract the spectral density of a number of molecular complexes from available experimental data. Specifically, we show that experimental data for dye molecules in several solvents, amino acid proteins in water, and some photochemical systems (e.g., rhodopsin and green fluorescence proteins), are well described by a three-parameter family of sub-Ohmic spectral densities that are characterized by a fast initial Gaussian-like decay followed by a slow algebraic-like decay rate at long times.
Detecting Density Variations and Nanovoids
Miller, Michael K [ORNL; Longstreth-Spoor, L. [Washington University, St. Louis; Kelton, K. F. [Washington University, St. Louis
2011-01-01T23:59:59.000Z
A combination of simulated and experimental data has been used to investigate the size range of nanovoids that can be detected in atom probe tomography data. Simulated atom probe tomography data have revealed that nanovoids as small as 1 nm in diameter can be detected in atom probe tomography data with the use of iso-density surfaces. Iso-density surfaces may be used to quantify the size, morphology and number density of nanovoids and other variations in density in atom probe tomography data. Experimental data from an aluminum-yttrium-iron metallic glass ribbon have revealed the effectiveness of this approach. Combining iso-density surfaces with atom maps also permits the segregation of solute to the nanovoids to be investigated. Field ion microscopy and thin section atom maps have also been used to detect pores and larger voids.
A lattice mesoscopic model of dynamically heterogeneous fluids
A. Lamura; S. Succi
2005-10-04T23:59:59.000Z
We introduce a mesoscopic three-dimensional Lattice Boltzmann Model which attempts to mimick the physical features associated with cage effects in dynamically heterogeneous fluids. To this purpose, we extend the standard Lattice Boltzmann dynamics with self-consistent constraints based on the non-local density of the surrounding fluid. The resulting dynamics exhibits typical features of dynamic heterogeneous fluids, such as non-Gaussian density distributions and long-time relaxation. Due to its intrinsically parallel dynamics, and absence of statistical noise, the method is expected to compute significantly faster than molecular dynamics, Monte Carlo and lattice glass models.
Dynamical multi-breakup processes in the {sup 124}Sn+{sup 64}Ni system at 35 MeV/nucleon
Papa, M.; Cardella, G.; De Filippo, E.; Giuliani, G.; Lanzano, G.; Pagano, A.; Pirrone, S.; Politi, G.; Porto, F.; Verde, G. [INFN, Sezione di Catania and Dipartimento di Fisica, Universita di Catania (Italy); Amorini, F.; Anzalone, A.; Bonasera, A.; Cavallaro, S.; Colonna, M.; Di Toro, M.; Giustolisi, F.; Iacono-Manno, M.; La Guidara, E.; Lanzalone, G. [INFN, Laboratori Nazionali del Sud and Dipartimento di Fisica, Universita di Catania (Italy)] (and others)
2007-05-15T23:59:59.000Z
Multi-breakup processes for the {sup 124}Sn+{sup 64}Ni system at 35 MeV/nucleon have been studied with the forward part of the CHIMERA detector. An extensive comparison between experimental data corresponding to almost complete ternary events and constrained molecular dynamics (CoMD-II) calculations suggests different characteristic times in the selected processes. This is in agreement with previous studies of the same reaction already published concerning the prompt intermediate-mass-fragment emission. Stimulated by CoMD-II calculations, we investigate the existence of more complex dynamical multi-breakup processes occurring on the same time scale. A detailed study of the rotational dynamics leading to slower dynamical fission processes is also presented.
Gong, Xingao
short course on density-functional theory lectures given at the Fudan University, Shanghai, January transforms Lecture 2: Density-functional theory Â· the electronic ground state as a functional of the external-order derivatives from (density-functional) perturbation theory Â· the 2n+1 theorem Â· lattice dynamics from DFPT
Nagy, A. [Department of Theoretical Physics, University of Debrecen, H-4010 Debrecen (Hungary)
2011-09-15T23:59:59.000Z
A link between density and pair density functional theories is presented. Density and pair density scaling are used to derive the Euler equation in both theories. Density scaling provides a constructive way of obtaining approximations for the Pauli potential. The Pauli potential (energy) of the density functional theory is expressed as the difference of the scaled and original exchange-correlation potentials (energies).
Hybrid Architectural Dynamic Thermal Management Kevin Skadron
Skadron, Kevin
. The challenge is that even though this reduction in power density reduces heat dissipation and can be usedÂ3 or more per watt of heat dissipated [1, 6], making it more difficult to deploy new systems. Cooling costs management (DTM) dynamically reduces the power density on the chip to maintain safe operating tem- peratures
Function and dynamics of aptamers: A case study on the malachite green aptamer
Wang, Tianjiao
2008-12-01T23:59:59.000Z
Aptamers are short single-stranded nucleic acids that can bind to their targets with high specificity and high affinity. To study aptamer function and dynamics, the malachite green aptamer was chosen as a model. Malachite green (MG) bleaching, in which an OH- attacks the central carbon (C1) of MG, was inhibited in the presence of the malachite green aptamer (MGA). The inhibition of MG bleaching by MGA could be reversed by an antisense oligonucleotide (AS) complementary to the MGA binding pocket. Computational cavity analysis of the NMR structure of the MGA-MG complex predicted that the OH{sup -} is sterically excluded from the C1 of MG. The prediction was confirmed experimentally using variants of the MGA with changes in the MG binding pocket. This work shows that molecular reactivity can be reversibly regulated by an aptamer-AS pair based on steric hindrance. In addition to demonstrate that aptamers could control molecular reactivity, aptamer dynamics was studied with a strategy combining molecular dynamics (MD) simulation and experimental verification. MD simulation predicted that the MG binding pocket of the MGA is largely pre-organized and that binding of MG involves reorganization of the pocket and a simultaneous twisting of the MGA terminal stems around the pocket. MD simulation also provided a 3D-structure model of unoccupied MGA that has not yet been obtained by biophysical measurements. These predictions were consistent with biochemical and biophysical measurements of the MGA-MG interaction including RNase I footprinting, melting curves, thermodynamic and kinetic constants measurement. This work shows that MD simulation can be used to extend our understanding of the dynamics of aptamer-target interaction which is not evident from static 3D-structures. To conclude, I have developed a novel concept to control molecular reactivity by an aptamer based on steric protection and a strategy to study the dynamics of aptamer-target interaction by combining MD simulation and experimental verification. The former has potential application in controlling metabolic reactions and protein modifications by small reactants and the latter may serve as a general approach to study the dynamics of aptamer-target interaction for new insights into mechanisms of aptamer-target recognition.
New Mexico, University of
Day 2014 at The University of New Mexico CHTM and OSE-ECE graduate student, Md. Mottaleb Hossain, won at The University of New Mexico, USA for his poster titled "Low voltage CMOS compatible linear-mode p-n junction works with Electrical and Computer Engineering Professor Majeed M. Hayat, CHTM Associate Director, OSE
Symmetries in open quantum dynamics
Thomas F. Jordan
2014-08-20T23:59:59.000Z
Simple examples are used to introduce and examine a Heisenberg picture of symmetries of open quantum dynamics that can be described by unitary operators. When the symmetries are for Hamiltonian dynamics of an entire system, and the spectrum of the Hamiltonian operator has a lower bound, the symmetry operators commute with the Hamiltonian operator. An example shows that symmetry operators need not commute with the Hamiltonian operator when the spectrum of the Hamiltonian does not have a lower bound. There are many more symmetries that are only for the open dynamics of a subsystem and are described by unitary operators that do not commute with the Hamiltonian for the dynamics of the entire system. Examples show how these symmetries alone can reveal properties of the dynamics and reduce what needs to be done to work out the dynamics. A symmetry of the open dynamics of a subsystem can imply properties of the dynamics for the entire system that are not implied by the symmetries of the dynamics of the entire system. The symmetries are generally not related to constants of the motion for the open dynamics of the subsystem. There are symmetries of the open dynamics of a subsystem that depend only on the dynamics. In the simplest examples, these are also symmetries of the dynamics of the entire system. There are many more symmetries, of a new kind, that also depend on correlations, or absence of correlations, between the subsystem and the rest of the entire system, or on the state of the rest of the entire system. Symmetries that depend on correlations generally cannot be seen in the Schr\\"{o}dinger picture as symmetries of dynamical maps of density matrices for the subsystem.
Covariant density functional theory for antimagnetic rotation
P. W. Zhao; J. Peng; H. Z. Liang; P. Ring; J. Meng
2012-05-04T23:59:59.000Z
Following the previous letter on the first microscopic description of the antimagnetic rotation (AMR) in 105Cd, a systematic investigation and detailed analysis for the AMR band in the frame-work of tilted axis cranking (TAC) model based on covariant density functional theory are carried out. After performing the microscopic and self-consistentTAC calculations with an given density functional, the configuration for the observed AMR band in 105Cd is obtained from the single-particle Routhians. With the configuration thus obtained, the tilt angle for a given rotational frequency is determined self-consistently by minimizing the total Routhian with respect to the tilt angle. In such a way, the energy spectrum, total angular momenta, kinetic and dynamic moments of inertia, and the B(E2) values for the AMR band in 105Cd are calculated. Good agreement with the data is found. By investigating microscopically the contributions from neutrons and protons to the total angular momentum, the "two-shears-like" mechanism in the AMR band is clearly illus-trated. Finally, the currents leading to time-odd mean fields in the Dirac equation are presented and discussed in detail. It is found that they are essentially determined by the valence particles and/or holes. Their spatial distribution and size depend onthe specific single-particle orbitals and the rotational frequency.
Longitudinal density monitor for the LHC
DOE Public Access Gateway for Energy & Science Beta (PAGES Beta)
Jeff, A.; Andersen, M.; Boccardi, A.; Bozyigit, S.; Bravin, E.; Lefevre, T.; Rabiller, A.; Roncarolo, F.; Welsch, C. P.; Fisher, A. S.
2012-03-01T23:59:59.000Z
The longitudinal density monitor (LDM) is primarily intended for the measurement of the particle population in nominally empty rf buckets. These so-called satellite or ghost bunches can cause problems for machine protection as well as influencing the luminosity calibration of the LHC. The high dynamic range of the system allows measurement of ghost bunches with as little as 0.01% of the main bunch population at the same time as characterization of the main bunches. The LDM is a single-photon counting system using visible synchrotron light. The photon detector is a silicon avalanche photodiode operated in Geiger mode, which allows the longitudinal distribution of the LHC beams to be measured with a resolution of 90 ps. Results from the LDM are presented, including a proposed method for constructing a 3-dimensional beam density map by scanning the LDM sensor in the transverse plane. In addition, we present a scheme to improve the sensitivity of the system by using an optical switching technique.
Considerations and Recent Advances in Molecular Dynamics Introduction
numbers of computers like Folding@Home, or utilizing extremely specialized hardware such as Anton, MD
Dynamics of capillary condensation in aerogels
Nomura, R.; Miyashita, W.; Yoneyama, K.; Okuda, Y. [Department of Condensed Matter Physics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8551 (Japan)
2006-03-15T23:59:59.000Z
Dynamics of capillary condensation of liquid {sup 4}He in various density silica aerogels was investigated systematically. Interfaces were clearly visible when bulk liquid was rapidly sucked into the aerogel. Time evolution of the interface positions was consistent with the Washburn model and their effective pore radii were obtained. Condensation was a single step in a dense aerogel and two steps in a low density aerogel. Crossover between the two types of condensation was observed in an intermediate density aerogel. Variety of the dynamics may be the manifestation of the fractal nature of aerogels which had a wide range of distribution of pore radii.
T. Thomas; P. Katgert
2005-10-10T23:59:59.000Z
We study the morphology-radius (MR-) and morphology-density (MD-) relations for a sample of about 850 galaxies (with M = -22), the S0 galaxies and the early spirals have different Sigma1-distributions. The reason for this is that Sigma1 is much less correlated with R than is Sigma10, and thus has much less cross-talk from the (MR-) relation. On average, the 'normal' ellipticals populate environments with higher projected density than do the S0 galaxies while the early spirals populate even less dense environments. The segregation of the brightest ellipticals and the late spirals is driven mostly by global factors, while the segregation between 'normal' ellipticals, S0 galaxies and early spirals is driven primarily by local factors.
Current density partitioning in time-dependent current density functional theory
Mosquera, Martín A. [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States)] [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States); Wasserman, Adam, E-mail: awasser@purdue.edu [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States) [Department of Chemistry, Purdue University, West Lafayette, Indiana 47907 (United States); Department of Physics, Purdue University, West Lafayette, Indiana 47907 (United States)
2014-05-14T23:59:59.000Z
We adapt time-dependent current density functional theory to allow for a fragment-based solution of the many-electron problem of molecules in the presence of time-dependent electric and magnetic fields. Regarding a molecule as a set of non-interacting subsystems that individually evolve under the influence of an auxiliary external electromagnetic vector-scalar potential pair, the partition 4-potential, we show that there are one-to-one mappings between this auxiliary potential, a sharply-defined set of fragment current densities, and the total current density of the system. The partition electromagnetic (EM) 4-potential is expressed in terms of the real EM 4-potential of the system and a gluing EM 4-potential that accounts for exchange-correlation effects and mutual interaction forces between fragments that are required to yield the correct electron dynamics. We prove the zero-force theorem for the fragmented system, establish a variational formulation in terms of action functionals, and provide a simple illustration for a charged particle in a ring.
Frontiers for Discovery in High Energy Density Physics
Davidson, R. C.; Katsouleas, T.; Arons, J.; Baring, M.; Deeney, C.; Di Mauro, L.; Ditmire, T.; Falcone, R.; Hammer, D.; Hill, W.; Jacak, B.; Joshi, C.; Lamb, F.; Lee, R.; Logan, B. G.; Melissinos, A.; Meyerhofer, D.; Mori, W.; Murnane, M.; Remington, B.; Rosner, R.; Schneider, D.; Silvera, I.; Stone, J.; Wilde, B.; Zajc. W.
2004-07-20T23:59:59.000Z
The report is intended to identify the compelling research opportunities of high intellectual value in high energy density physics. The opportunities for discovery include the broad scope of this highly interdisciplinary field that spans a wide range of physics areas including plasma physics, laser and particle beam physics, nuclear physics, astrophysics, atomic and molecular physics, materials science and condensed matter physics, intense radiation-matter interaction physics, fluid dynamics, and magnetohydrodynamics
EPR measurement and the origin of cosmic density fluctuations
Masahiro Morikawa
2012-11-08T23:59:59.000Z
We explore consistent application of quantum mechanics to the objects in the Universe and in laboratories. The measurement dynamics in quantum mechanics is modeled as a physical process of spontaneous symmetry breaking (SSB) which is described by the generalized effective action method. A violation of the Bell inequality is observed in this model and the generation of the density fluctuations in the early Universe is described as the SSB process of the spatially translational symmetry.
EPR measurement and the origin of cosmic density fluctuations
Morikawa, Masahiro
2012-01-01T23:59:59.000Z
We explore consistent application of quantum mechanics to the objects in the Universe and in laboratories. The measurement dynamics in quantum mechanics is modeled as a physical process of spontaneous symmetry breaking (SSB) which is described by the generalized effective action method. A violation of the Bell inequality is observed in this model and the generation of the density fluctuations in the early Universe is described as the SSB process of the spatially translational symmetry.
Local thermodynamic equilibrium in rapidly heated high energy density plasmas
Aslanyan, V.; Tallents, G. J. [York Plasma Institute, Department of Physics, University of York, Heslington, York YO10 5DD (United Kingdom)
2014-06-15T23:59:59.000Z
Emission spectra and the dynamics of high energy density plasmas created by optical and Free Electron Lasers (FELs) depend on the populations of atomic levels. Calculations of plasma emission and ionization may be simplified by assuming Local Thermodynamic Equilibrium (LTE), where populations are given by the Saha-Boltzmann equation. LTE can be achieved at high densities when collisional processes are much more significant than radiative processes, but may not be valid if plasma conditions change rapidly. A collisional-radiative model has been used to calculate the times taken by carbon and iron plasmas to reach LTE at varying densities and heating rates. The effect of different energy deposition methods, as well as Ionization Potential Depression are explored. This work shows regimes in rapidly changing plasmas, such as those created by optical lasers and FELs, where the use of LTE is justified, because timescales for plasma changes are significantly longer than the times needed to achieve an LTE ionization balance.
Density waves in the shearing sheet III. Disc heating
B. Fuchs
2001-04-25T23:59:59.000Z
The problem of dynamical heating of galactic discs by spiral density waves is discussed using the shearing sheet model. The secular evolution of the disc is described quantitatively by a diffusion equation for the distribution function of stars in the space spanned by integrals of motion of the stars, in particular the radial action integral and an integral related to the angular momentum. Specifically, disc heating by a succession of transient, `swing amplified' density waves is studied. It is shown that such density waves lead predominantly to diffusion of stars in radial action space. The stochastical changes of angular momenta of the stars and the corresponding stochastic changes of the guiding centre radii of the stellar orbits induced by this process are much smaller.
Transverse charge and magnetization densities in the nucleon's chiral periphery
Granados, Carlos G. [JLAB Newport News, VA (United States); Weiss, Christian [JLAB Newport News, VA (United States)
2014-01-01T23:59:59.000Z
In the light-front description of nucleon structure the electromagnetic form factors are expressed in terms of frame-independent transverse densities of charge and magnetization. Recent work has studied the transverse densities at peripheral distances b = O(M{pi}{sup -1}), where they are governed by universal chiral dynamics and can be computed in a model-independent manner. Of particular interest is the comparison of the peripheral charge and magnetization densities. We summarize (a) their interpretation as spin-independent and -dependent current matrix elements; (b) the leading-order chiral effective field theory results; (c) their mechanical interpretation in the light-front formulation; (d) the large-N_c limit of QCD and the role of {Delta} intermediate states; (e) the connection with generalized parton distributions and peripheral high-energy scattering processes.
Intercrystalline density on nanocrystalline nickel
Haasz, T.R.; Aust, K.T. [Univ. of Toronto, Ontario (Canada). Dept. of Metallurgy and Materials Science] [Univ. of Toronto, Ontario (Canada). Dept. of Metallurgy and Materials Science; Palumbo, G. [Ontario Hydro Research Div., Toronto, Ontario (Canada)] [Ontario Hydro Research Div., Toronto, Ontario (Canada); El-Sherik, A.M.; Erb, U. [Queen`s Univ., Kingston, Ontario (Canada). Dept. of Materials and Metallurgical Engineering] [Queen`s Univ., Kingston, Ontario (Canada). Dept. of Materials and Metallurgical Engineering
1995-02-01T23:59:59.000Z
Most methods currently available for the synthesis of nanostructured materials result in considerable residual porosity. Studies concerned with the novel structures and properties of these materials are thus compromised by the intrinsically high levels of porosity. As recently shown by Kristic et al., porosity can have a significant effect on fundamental materials properties such as Young`s modulus. One of the most promising techniques for the production of fully dense nanocrystalline materials is electrodeposition. In the present work, the residual porosity and density of nanostructured nickel produced by the electrodeposition method is assessed and discussed in light of the intrinsic intercrystalline density of nickel.
Time Dependent Density Functional Theory An introduction
Botti, Silvana
Time Dependent Density Functional Theory An introduction Francesco Sottile LSI, Ecole Polytechnique (ETSF) Time Dependent Density Functional Theory Palaiseau, 7 February 2012 1 / 32 #12;Outline 1 Frontiers 4 Perspectives and Resources Francesco Sottile (ETSF) Time Dependent Density Functional Theory
Time Dependent Density Functional Theory An Introduction
Botti, Silvana
Time Dependent Density Functional Theory An Introduction Francesco Sottile Laboratoire des Solides) Belfast, 29 Jun 2007 Time Dependent Density Functional Theory Francesco Sottile #12;Intro Formalism Dependent Density Functional Theory Francesco Sottile #12;Intro Formalism Results Resources Outline 1
Statistical density modification using local pattern matching
Terwilliger, Thomas C.
2007-01-23T23:59:59.000Z
A computer implemented method modifies an experimental electron density map. A set of selected known experimental and model electron density maps is provided and standard templates of electron density are created from the selected experimental and model electron density maps by clustering and averaging values of electron density in a spherical region about each point in a grid that defines each selected known experimental and model electron density maps. Histograms are also created from the selected experimental and model electron density maps that relate the value of electron density at the center of each of the spherical regions to a correlation coefficient of a density surrounding each corresponding grid point in each one of the standard templates. The standard templates and the histograms are applied to grid points on the experimental electron density map to form new estimates of electron density at each grid point in the experimental electron density map.
Open problems in nuclear density functional theory
B. G. Giraud
2009-11-30T23:59:59.000Z
This note describes five subjects of some interest for the density functional theory in nuclear physics. These are, respectively, i) the need for concave functionals, ii) the nature of the Kohn-Sham potential for the radial density theory, iii) a proper implementation of a density functional for an "intrinsic" rotational density, iv) the possible existence of a potential driving the square root of the density, and v) the existence of many models where a density functional can be explicitly constructed.
Transformations for densities Linear transformations
Adler, Robert J.
' & $ % Lecture 28 Transformations for densities Linear transformations 1-1 differentiable functions General transformations Expectation of a function 1 #12;' & $ % Transformations for discrete transformation of a U[0, 1] Â· Take X U[0, 1], so that fX(x) = 1 0 0 and set Y
Complex Dynamics Bernardo Da Costa, Koushik Ramachandran, Jingjing Qu, and I had a two semester learning seminar in complex analysis and potential ...
Krishna, Rajamani; van Baten, Jasper M
2011-01-01T23:59:59.000Z
Molecular Dynamics (MD) simulations were carried out to determine the self-diffusivitiy, D{sub i,self}, the Maxwell–Stefan diffusivity, Ð{sub i}, and the Fick diffusivity, D{sub i}, for methane (C1), ethane (C2), propane (C3), n-butane (nC4), n-pentane (nC5), n-hexane (nC6), n-heptane (nC7), and cyclohexane (cC6) in cylindrical silica mesopores for a range of pore concentrations. The MD simulations show that zero-loading diffusivity Ð{sub i}(0) is consistently lower, by up to a factor of 20, than the values anticipated by the classical Knudsen formula. The concentration dependence of the Fick diffusivity, D{sub i} is found to be unusually complex, and displays a strong minimum in some cases; this characteristic can be traced to molecular clustering.
Zhao, Junhua, E-mail: junhua.zhao@uni-weimar.de [Jiangsu Province Key Laboratory of Advanced Manufacturing Equipment and Technology of Food, Jiangnan University, 214122 Wuxi (China) [Jiangsu Province Key Laboratory of Advanced Manufacturing Equipment and Technology of Food, Jiangnan University, 214122 Wuxi (China); Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany); Jiang, Jin-Wu, E-mail: jwjiang5918@hotmail.com [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany)] [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany); Rabczuk, Timon, E-mail: timon.rabczuk@uni-weimar.de [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany) [Institute of Structural Mechanics, Bauhaus-University Weimar, 99423 Weimar (Germany); School of Civil, Environmental and Architectural Engineering, Korea University, 136-701 Seoul (Korea, Republic of)
2013-12-02T23:59:59.000Z
The temperature-dependent mechanical properties of single-layer molybdenum disulphide (MoS{sub 2}) are obtained using molecular dynamics (MD) nanoindentation simulations. The Young's moduli, maximum load stress, and maximum loading strain decrease with increasing temperature from 4.2?K to 500?K. The obtained Young's moduli are in good agreement with those using our MD uniaxial tension simulations and the available experimental results. The tendency of maximum loading strain with different temperature is opposite with that of metal materials due to the short range Stillinger-Weber potentials in MoS{sub 2}. Furthermore, the indenter tip radius and fitting strain effect on the mechanical properties are also discussed.
Relativistic Nuclear Energy Density Functionals: adjusting parameters to binding energies
T. Niksic; D. Vretenar; P. Ring
2008-09-08T23:59:59.000Z
We study a particular class of relativistic nuclear energy density functionals in which only nucleon degrees of freedom are explicitly used in the construction of effective interaction terms. Short-distance (high-momentum) correlations, as well as intermediate and long-range dynamics, are encoded in the medium (nucleon density) dependence of the strength functionals of an effective interaction Lagrangian. Guided by the density dependence of microscopic nucleon self-energies in nuclear matter, a phenomenological ansatz for the density-dependent coupling functionals is accurately determined in self-consistent mean-field calculations of binding energies of a large set of axially deformed nuclei. The relationship between the nuclear matter volume, surface and symmetry energies, and the corresponding predictions for nuclear masses is analyzed in detail. The resulting best-fit parametrization of the nuclear energy density functional is further tested in calculations of properties of spherical and deformed medium-heavy and heavy nuclei, including binding energies, charge radii, deformation parameters, neutron skin thickness, and excitation energies of giant multipole resonances.
Pion transverse charge density and the edge of hadrons
Carmignotto, Marco [Catholic University of America; Horn, Tanja [Catholic University of America; Miller, Gerald A. [University of Washington
2014-08-01T23:59:59.000Z
We use the world data on the pion form factor for space-like kinematics and a technique used to extract the proton transverse densities, to extract the transverse pion charge density and its uncertainty due to experimental uncertainties and incomplete knowledge of the pion form factor at large values of Q2. The pion charge density at small values of b<0.1 fm is dominated by this incompleteness error while the range between 0.1-0.3 fm is relatively well constrained. A comparison of pion and proton charge densities shows that the pion is denser than the proton for values of b<0.2 fm. The pion and proton distributions seem to be the same for values of b=0.2-0.6 fm. Future data from Jlab 12 GeV and the EIC will increase the dynamic extent of the data to higher values of Q2 and thus reduce the uncertainties in the extracted pion charge density.
Biosystem Dynamics & Design | EMSL
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Biosystem Dynamics & Design Overview Atmospheric Aerosol Systems Biosystem Dynamics & Design Energy Materials & Processes Terrestrial & Subsurface Ecosystems Biosystem Dynamics &...
Ullmer, Brygg
PREDICTION OF CUTTINGS BED HEIGHT WITH COMPUTATIONAL FLUID DYNAMICS IN DRILLING HORIZONTAL parameters such as wellbore geometry, pump rate, drilling fluid rheology and density, and maximum drilling Computational Fluid Dynamics methods. Movement, concentration and accumulation of drilled cuttings in non
Jacek Dobaczewski Density functional theory and energy
Dobaczewski, Jacek
Jacek Dobaczewski Density functional theory and energy density functionals in nuclear physics Jacek Functional #12;Jacek Dobaczewski Mean-Field Theory Density Functional Theory Â· mean-field one? Density Functional Theory: A variational method that uses observables as variational parameters. #12;Jacek
Density Functional Theory (DFT) Rob Parrish
Sherrill, David
Density Functional Theory (DFT) Rob Parrish robparrish@gmail.com 1 #12;Agenda Â· The mechanism Easy to do this Why? Because of Hermitian Operators: Kinetic Energy Density: #12;Density Functional The density completely defines the observable state of the system: The way in which it does so (the functional
A current density distribution tool
Jagush, Frederic A.
1989-01-01T23:59:59.000Z
. I. INTRODUCTION Current density distribution is an important consideration for those involved in electrochemical systems and electroplating in particular. In the printed wiring board (PWB) business, great emphasis is placed on the study of current... exist. Numerical techniques on the other hand, are usually easy to implement and are easily applicable to microcomputers. Their disadvantage as with any approximation technique is that the exactness of the results with This document follows the style...
Arnold, Jonathan
de Bogota, Colombia in 1992, his M.Sc. in clinical microbiology from the University of London, St and Antimicrobial Resistance Unit, Universidad El Bosque, located in Colombia, South America. Cesar A. Arias, MD
Probability distribution of the vacuum energy density
Duplancic, Goran; Stefancic, Hrvoje [Theoretical Physics Division, Rudjer Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia); Glavan, Drazen [Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 331, HR-10002 Zagreb (Croatia)
2010-12-15T23:59:59.000Z
As the vacuum state of a quantum field is not an eigenstate of the Hamiltonian density, the vacuum energy density can be represented as a random variable. We present an analytical calculation of the probability distribution of the vacuum energy density for real and complex massless scalar fields in Minkowski space. The obtained probability distributions are broad and the vacuum expectation value of the Hamiltonian density is not fully representative of the vacuum energy density.
Accelerated molecular dynamics methods: introduction and recent developments
Uberuaga, Blas Pedro [Los Alamos National Laboratory; Voter, Arthur F [Los Alamos National Laboratory; Perez, Danny [Los Alamos National Laboratory; Shim, Y [UNIV OF TOLEDO; Amar, J G [UNIV OF TOLEDO
2009-01-01T23:59:59.000Z
A long-standing limitation in the use of molecular dynamics (MD) simulation is that it can only be applied directly to processes that take place on very short timescales: nanoseconds if empirical potentials are employed, or picoseconds if we rely on electronic structure methods. Many processes of interest in chemistry, biochemistry, and materials science require study over microseconds and beyond, due either to the natural timescale for the evolution or to the duration of the experiment of interest. Ignoring the case of liquids xxx, the dynamics on these time scales is typically characterized by infrequent-event transitions, from state to state, usually involving an energy barrier. There is a long and venerable tradition in chemistry of using transition state theory (TST) [10, 19, 23] to directly compute rate constants for these kinds of activated processes. If needed dynamical corrections to the TST rate, and even quantum corrections, can be computed to achieve an accuracy suitable for the problem at hand. These rate constants then allow them to understand the system behavior on longer time scales than we can directly reach with MD. For complex systems with many reaction paths, the TST rates can be fed into a stochastic simulation procedure such as kinetic Monte Carlo xxx, and a direct simulation of the advance of the system through its possible states can be obtained in a probabilistically exact way. A problem that has become more evident in recent years, however, is that for many systems of interest there is a complexity that makes it difficult, if not impossible, to determine all the relevant reaction paths to which TST should be applied. This is a serious issue, as omitted transition pathways can have uncontrollable consequences on the simulated long-time kinetics. Over the last decade or so, we have been developing a new class of methods for treating the long-time dynamics in these complex, infrequent-event systems. Rather than trying to guess in advance what reaction pathways may be important, we return instead to a molecular dynamics treatment, in which the trajectory itself finds an appropriate way to escape from each state of the system. Since a direct integration of the trajectory would be limited to nanoseconds, while we are seeking to follow the system for much longer times, we modify the dynamics in some way to cause the first escape to happen much more quickly, thereby accelerating the dynamics. The key is to design the modified dynamics in a way that does as little damage as possible to the probability for escaping along a given pathway - i.e., we try to preserve the relative rate constants for the different possible escape paths out of the state. We can then use this modified dynamics to follow the system from state to state, reaching much longer times than we could reach with direct MD. The dynamics within any one state may no longer be meaningful, but the state-to-state dynamics, in the best case, as we discuss in the paper, can be exact. We have developed three methods in this accelerated molecular dynamics (AMD) class, in each case appealing to TST, either implicitly or explicitly, to design the modified dynamics. Each of these methods has its own advantages, and we and others have applied these methods to a wide range of problems. The purpose of this article is to give the reader a brief introduction to how these methods work, and discuss some of the recent developments that have been made to improve their power and applicability. Note that this brief review does not claim to be exhaustive: various other methods aiming at similar goals have been proposed in the literature. For the sake of brevity, our focus will exclusively be on the methods developed by the group.
Rau, Don C.
by respondent identification. Thus, data security plans must be tailored to the unique needs and concerns of each data set: a "one-security-plan-fits-all" approach is neither feasible nor desirable. Nevertheless
citation: Natio Hyattsville, MD
Illinois at Chicago, University of
Reform 75 Monitoring Health Care Reform: SelfReports of Health Insurance Premium Assistance & Program SESSION 1 SUMMARY 71 KAREN CYBULSKI, ANNE CIEMNECKI, AND KAREN BOGEN SESSION 2: Monitoring Health Care Survey 101 MARC W. ZODET, STEVEN C. HILL, AND SAMUEL H. ZUVEKAS The RWJF Health Care Public
Training Session: Frederick, MD
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This 3.5-hour training provides builders with a comprehensive review of zero net-energy-ready home construction including the business case, detailed specifications, and opportunities to be...
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AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE:1 First Use of Energy for All Purposes (Fuel and Nonfuel),Feet) Year Jan Feb Mar Apr MayAtmosphericNuclear Security Administration the1 -theErik Spoerke SSLS ExhibitIowaLos Alamos National LaboratoryEngineersMASKMD CINT
Assumptions that imply quantum dynamics is linear
Thomas F. Jordan
2006-01-26T23:59:59.000Z
A basic linearity of quantum dynamics, that density matrices are mapped linearly to density matrices, is proved very simply for a system that does not interact with anything else. It is assumed that at each time the physical quantities and states are described by the usual linear structures of quantum mechanics. Beyond that, the proof assumes only that the dynamics does not depend on anything outside the system but must allow the system to be described as part of a larger system. The basic linearity is linked with previously established results to complete a simple derivation of the linear Schrodinger equation. For this it is assumed that density matrices are mapped one-to-one onto density matrices. An alternative is to assume that pure states are mapped one-to-one onto pure states and that entropy does not decrease.
Density functional theory of electrowetting
Markus Bier; Ingrid Ibagon
2014-02-10T23:59:59.000Z
The phenomenon of electrowetting, i.e., the dependence of the macroscopic contact angle of a fluid on the electrostatic potential of the substrate, is analyzed in terms of the density functional theory of wetting. It is shown that electrowetting is not an electrocapillarity effect, i.e., it cannot be consistently understood in terms of the variation of the substrate-fluid interfacial tension with the electrostatic substrate potential, but it is related to the depth of the effective interface potential. The key feature, which has been overlooked so far and which occurs naturally in the density functional approach is the structural change of a fluid if it is brought into contact with another fluid. These structural changes occur in the present context as the formation of finite films of one fluid phase in between the substrate and the bulk of the other fluid phase. The non-vanishing Donnan potentials (Galvani potential differences) across such film-bulk fluid interfaces, which generically occur due to an unequal partitioning of ions as a result of differences of solubility contrasts, lead to correction terms in the electrowetting equation, which become relevant for sufficiently small substrate potentials. Whereas the present density functional approach confirms the commonly used electrocapillarity-based electrowetting equation as a good approximation for the cases of metallic electrodes or electrodes coated with a hydrophobic dielectric in contact with an electrolyte solution and an ion-free oil, a significantly reduced tendency for electrowetting is predicted for electrodes coated with a dielectric which is hydrophilic or which is in contact with two immiscible electrolyte solutions.
Affine maps of density matrices
Thomas F. Jordan
2004-11-21T23:59:59.000Z
For quantum systems described by finite matrices, linear and affine maps of matrices are shown to provide equivalent descriptions of evolution of density matrices for a subsystem caused by unitary Hamiltonian evolution in a larger system; an affine map can be replaced by a linear map, and a linear map can be replaced by an affine map. There may be significant advantage in using an affine map. The linear map is generally not completely positive, but the linear part of an equivalent affine map can be chosen to be completely positive and related in the simplest possible way to the unitary Hamiltonian evolution in the larger system.
Combining Density Functional Theory and Density Matrix Functional Theory Daniel R. Rohr1
Paris-Sud XI, UniversitÃ© de
Combining Density Functional Theory and Density Matrix Functional Theory Daniel R. Rohr1 , Julien and CNRS, 4 place Jussieu, 75252 Paris, France We combine density-functional theory with density cleavage is an ubiquitous process for chemistry. Density-matrix functional theory (DMFT) (see, e.g., Refs
Decoherence rates for Galilean covariant dynamics
Jeremy Clark
2008-04-02T23:59:59.000Z
We introduce a measure of decoherence for a class of density operators. For Gaussian density operators in dimension one it coincides with an index used by Morikawa (1990). Spatial decoherence rates are derived for three large classes of the Galilean covariant quantum semigroups introduced by Holevo. We also characterize the relaxation to a Gaussian state for these dynamics and give a theorem for the convergence of the Wigner function to the probability distribution of the classical analog of the process.
High density behaviour of nuclear symmetry energy
D. N. Basu; Tapan Mukhopadhyay
2006-12-27T23:59:59.000Z
Role of the isospin asymmetry in nuclei and neutron stars, with an emphasis on the density dependence of the nuclear symmetry energy, is discussed. The symmetry energy is obtained using the isoscalar as well as isovector components of the density dependent M3Y effective interaction. The constants of density dependence of the effective interaction are obtained by reproducing the saturation energy per nucleon and the saturation density of spin and isospin symmetric cold infinite nuclear matter. Implications for the density dependence of the symmetry energy in case of a neutron star are discussed, and also possible constraints on the density dependence obtained from finite nuclei are compared.
Collective dynamics of active filament complexes
Nogucci, Hironobu
2015-01-01T23:59:59.000Z
Networks of biofilaments are essential for the formation of cellular structures and they support various biological functions. Previous studies have largely investigated the collective dynamics of rod-like biofilaments; however, the shapes of actual subcelluar componensts are often more elaborate. In this study, we investigated an active object composed of two active filaments, which represents a progression from rod-like biofilaments to complex-shaped biofilaments. Specifically, we numerically assessed the collective behaviors of these active objects and observed several types of dynamics depending on the density and the angle of the two filaments as shape parameters of the object. Among the observed collective dynamics, moving density bands that we named 'moving smectic' are reported here for the first time. By using statistical analyses of the orbits of individual objects and the interactions among them, the mechanisms underlying the rise of these dynamics patterns in the system were determined. This study...
Dynamics of clusters and molecules in contact with an environment
Giraud, Olivier
(embedded, deposited) Fundamental studies on mechanisms (irradiation, deposition) (Nano) Contacts with insulators (ionic crystals, rare gases...) Low energy dynamics (optical response, deposition) Laser irradiation #12;Time Dependent Density Functional Theory (TDDFT) Ensemble of orbitals (1 electron
Subsystem real-time Time Dependent Density Functional Theory
Krishtal, Alisa; Pavanello, Michele
2015-01-01T23:59:59.000Z
We present the extension of Frozen Density Embedding (FDE) theory to real-time Time Dependent Density Functional Theory (rt-TDDFT). FDE a is DFT-in-DFT embedding method that allows to partition a larger Kohn-Sham system into a set of smaller, coupled Kohn-Sham systems. Additional to the computational advantage, FDE provides physical insight into the properties of embedded systems and the coupling interactions between them. The extension to rt-TDDFT is done straightforwardly by evolving the Kohn-Sham subsystems in time simultaneously, while updating the embedding potential between the systems at every time step. Two main applications are presented: the explicit excitation energy transfer in real time between subsystems is demonstrated for the case of the Na$_4$ cluster and the effect of the embedding on optical spectra of coupled chromophores. In particular, the importance of including the full dynamic response in the embedding potential is demonstrated.
Density waves in the shearing sheet I. Swing amplification
B. Fuchs
2001-03-02T23:59:59.000Z
The shearing sheet model of a galactic disk is studied anew. The theoretical description of its dynamics is based on three building blocks: Stellar orbits, which are described here in epicyclic approximation, the collisionless Boltzmann equation determining the distribution function of stars in phase space, and the Poisson equation in order to take account of the self-gravity of the disk. Using these tools I develop a new formalism to describe perturbations of the shearing sheet. Applying this to the unbounded shearing sheet model I demonstrate again how the disturbances of the disk evolve always into `swing amplified' density waves, i.e. spiral-arm like, shearing density enhancements, which grow and decay while the wave crests swing by from leading to trailing orientation. Several examples are given how such `swing amplification' events are incited in the shearing sheet.
"Dark energy" as conformal dynamics of space
D. Burlankov
2006-10-23T23:59:59.000Z
The exact solution for dynamic of conform-flat space homogeneous since dynamic equation is given. Conform mode of space metric changing in Global time theory has negative energy density. Swap of energy to this mode from another ones lead to increasing of Universe homogeneity although probability of this swap from local objects is negligibly small. Conform mode is corresponding to "dark energy" in observation astronomy.
A molecular dynamics study of nuclear quantum effect on the diffusion of hydrogen in condensed phase
Nagashima, Hiroki; Tokumasu, Takashi [Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai, Miyagi (Japan); Tsuda, Shin-ichi [Shinshu University, 77-7 Minamibori, Nagano, Nagano (Japan); Tsuboi, Nobuyuki [Kyushu Institute of Technology, 1-1 Sensui-cho, Tobata-ku, Kitakyushu, Fukuoka (Japan); Koshi, Mitsuo [Yokohama National University, 79-7 Tokiwadai, Hodogaya, Yokohama, Kanagawa (Japan); Hayashie, A. Koichi [AoyamaGakuin University, 5-10-1 Fuchinobe, Chuo-ku, Sagamihara, Kanagawa (Japan)
2014-10-06T23:59:59.000Z
In this paper, the quantum effect of hydrogen molecule on its diffusivity is analyzed using Molecular Dynamics (MD) method. The path integral centroid MD (CMD) method is applied for the reproduction method of time evolution of the molecules. The diffusion coefficient of liquid hydrogen is calculated using the Green-Kubo method. The simulation is performed at wide temperature region and the temperature dependence of the quantum effect of hydrogen molecule is addressed. The calculation results are compared with those of classical MD results. As a result, it is confirmed that the diffusivity of hydrogen molecule is changed depending on temperature by the quantum effect. It is clarified that this result can be explained that the dominant factor by quantum effect on the diffusivity of hydrogen changes from the swollening the potential to the shallowing the potential well around 30 K. Moreover, it is found that this tendency is related to the temperature dependency of the ratio of the quantum kinetic energy and classical kinetic energy.
Risk Bounds for Mixture Density Estimation
Rakhlin, Alexander
2004-01-27T23:59:59.000Z
In this paper we focus on the problem of estimating a bounded density using a finite combination of densities from a given class. We consider the Maximum Likelihood Procedure (MLE) and the greedy procedure described by ...
Nonstatistical dynamics on the caldera
Peter Collins; Zeb C. Kramer; Barry K. Carpenter; Gregory S. Ezra; Stephen Wiggins
2014-05-09T23:59:59.000Z
We explore both classical and quantum dynamics of a model potential exhibiting a caldera: that is, a shallow potential well with two pairs of symmetry related index one saddles associated with entrance/exit channels. Classical trajectory simulations at several different energies confirm the existence of the `dynamical matching' phenomenon originally proposed by Carpenter, where the momentum direction associated with an incoming trajectory initiated at a high energy saddle point determines to a considerable extent the outcome of the reaction (passage through the diametrically opposing exit channel). By studying a `stretched' version of the caldera model, we have uncovered a generalized dynamical matching: bundles of trajectories can reflect off a hard potential wall so as to end up exiting predominantly through the transition state opposite the reflection point. We also investigate the effects of dissipation on the classical dynamics. In addition to classical trajectory studies, we examine the dynamics of quantum wave packets on the caldera potential (stretched and unstretched). These computations reveal a quantum mechanical analogue of the `dynamical matching' phenomenon, where the initial expectation value of the momentum direction for the wave packet determines the exit channel through which most of the probability density passes to product.
Quantum critical benchmark for density functional theory
Paul E. Grabowski; Kieron Burke
2014-08-09T23:59:59.000Z
Two electrons at the threshold of ionization represent a severe test case for electronic structure theory. A pseudospectral method yields a very accurate density of the two-electron ion with nuclear charge close to the critical value. Highly accurate energy components and potentials of Kohn-Sham density functional theory are given, as well as a useful parametrization of the critical density. The challenges for density functional approximations and the strength of correlation are also discussed.
Oxides having high energy densities
Ceder, Gerbrand; Kang, Kisuk
2013-09-10T23:59:59.000Z
Certain disclosed embodiments generally relate to oxide materials having relatively high energy and/or power densities. Various aspects of the embodiments are directed to oxide materials having a structure B.sub.i(M.sub.jY.sub.k)O.sub.2, for example, a structure Li.sub.j(Ni.sub.jY.sub.k)O.sub.2 such as Li(Ni.sub.0.5Mn.sub.0.5)O.sub.2. In this structure, Y represents one or more atoms, each independently selected from the group consisting of alkaline earth metals, transition metals, Group 14 elements, Group 15, or Group 16 elements. In some embodiments, such an oxide material may have an O3 crystal structure, and/or a layered structure such that the oxide comprises a plurality of first, repeating atomic planes comprising Li, and a plurality of second, repeating atomic planes comprising Ni and/or Y.
Shirley, Yancy L
2015-01-01T23:59:59.000Z
The optically thin critical densities and the effective excitation densities to produce a 1 K km/s (or 0.818 Jy km/s $(\\frac{\
Density Functional Theory Models for Radiation Damage
Density Functional Theory Models for Radiation Damage S.L. Dudarev EURATOM/CCFE Fusion Association, DFT Abstract Density functional theory models developed over the past decade provide unique phenomena. Density functional theory models have effectively created a new paradigm for the scientific
Time Dependent Density Functional Theory An introduction
Botti, Silvana
Time Dependent Density Functional Theory An introduction Francesco Sottile LSI, Ecole Polytechnique) Time Dependent Density Functional Theory Palaiseau, 26 May 2014 1 / 62 #12;Outline 1 Introduction: why and Resources Francesco Sottile (ETSF) Time Dependent Density Functional Theory Palaiseau, 26 May 2014 2 / 62
DENSITY FUNCTIONAL THEORY OF FIELD THEORETICAL SYSTEMS
Engel, Eberhard
DENSITY FUNCTIONAL THEORY OF FIELD THEORETICAL SYSTEMS E. Engel Inst. fur Theor. Physik background of relativistic density functional theory is emphasized and its consequences for relativistic Kohn-Sham equations are shown. The local density approximation for the exchange energy functional is reviewed
Density functional theory George F. Bertsch
Bertsch George F.
Density functional theory George F. Bertsch #3; Institute for Nuclear Theory and Department of Physics University of Tsukuba Tsukuba 305-8577 Japan Abstract Density functional theory is a remarkably Time-dependent density functional theory: the equations 34 A Optical properties
DENSITY FUNCTIONAL THEORY, THE MODERN TREATMENT OF
Gross, E.K.U.
DENSITY FUNCTIONAL THEORY, THE MODERN TREATMENT OF ELECTRON CORRELATIONS E.K.U. Gross and Stefan The basic idea of density functional theory is to describe a many-electron system exclusively and completely-consistent scheme, known as the Kohn-Sham scheme [2], is the heart of modern density functional theory
Molecular dynamics simulation: a tool for exploration and discovery using simple models
D. C. Rapaport
2014-11-13T23:59:59.000Z
Emergent phenomena share the fascinating property of not being obvious consequences of the design of the system in which they appear. This characteristic is no less relevant when attempting to simulate such phenomena, given that the outcome is not always a foregone conclusion. The present survey focuses on several simple model systems that exhibit surprisingly rich emergent behavior, all studied by MD simulation. The examples are taken from the disparate fields of fluid dynamics, granular matter and supramolecular self-assembly. In studies of fluids modeled at the detailed microscopic level using discrete particles, the simulations demonstrate that complex hydrodynamic phenomena in rotating and convecting fluids, the Taylor-Couette and Rayleigh-B\\'enard instabilities, can not only be observed within the limited length and time scales accessible to MD, but even quantitative agreement can be achieved. Simulation of highly counterintuitive segregation phenomena in granular mixtures, again using MD methods, but now augmented by forces producing damping and friction, leads to results that resemble experimentally observed axial and radial segregation in the case of a rotating cylinder, and to a novel form of horizontal segregation in a vertically vibrated layer. Finally, when modeling self-assembly processes analogous to the formation of the polyhedral shells that package spherical viruses, simulation of suitably shaped particles reveals the ability to produce complete, error-free assembly, and leads to the important general observation that reversible growth steps contribute to the high yield. While there are limitations to the MD approach, both computational and conceptual, the results offer a tantalizing hint of the kinds of phenomena that can be explored, and what might be discovered when sufficient resources are brought to bear on a problem.
Andrey Pototsky; Andrew J. Archer; Sergey E. Savel'ev; Uwe Thiele; Fabio Marchesoni
2011-03-15T23:59:59.000Z
We consider the unidirectional particle transport in a suspension of colloidal particles which interact with each other via a pair potential having a hard-core repulsion plus an attractive tail. The colloids are confined within a long narrow channel and are driven along by a DC or an AC external potential. In addition, the walls of the channel interact with the particles via a ratchet-like periodic potential. We use dynamical density functional theory to compute the average particle current. In the case of DC drive, we show that as the attraction strength between the colloids is increased beyond a critical value, the stationary density distribution of the particles loses its stability leading to depinning and a time dependent density profile. Attraction induced symmetry breaking gives rise to the coexistence of stable stationary density profiles with different spatial periods and time-periodic density profiles, each characterized by different values for the particle current.
The Second Peak: The Dark-Energy Density and the Cosmic Microwave Background
Marc Kamionkowski; Ari Buchalter
2000-01-05T23:59:59.000Z
Supernova evidence for a negative-pressure dark energy (e.g., cosmological constant or quintessence) that contributes a fraction $\\Omega_\\Lambda\\simeq0.7$ of closure density has been bolstered by the discrepancy between the total density, $\\Omega_{\\rm tot}\\simeq1$, suggested by the location of the first peak in the cosmic microwave background (CMB) power spectrum and the nonrelativistic-matter density $\\Omega_m\\simeq0.3$ obtained from dynamical measurements. Here we show that the impending identification of the location of the {\\it second} peak in the CMB power spectrum will provide an immediate and independent probe of the dark-energy density. As an aside, we show how the measured height of the first peak probably already points toward a low matter density and places upper limits to the reionization optical depth and gravitational-wave amplitude.
Jump conditions and dynamic surface tension at permeable interfaces such as the inner core boundary
Jump conditions and dynamic surface tension at permeable interfaces such as the inner core boundary as the density and viscosity changes. Independently of any intrinsic surface tension, a dynamic surface tension, a possibly anisotropic surface tension and terms including an interface mass density. In pratice
Aerodynamic Focusing Of High-Density Aerosols
Ruiz, D. E.; Fisch, Nathaniel
2014-02-24T23:59:59.000Z
High-density micron-sized particle aerosols might form the basis for a number of applications in which a material target with a particular shape might be quickly ionized to form a cylindrical or sheet shaped plasma. A simple experimental device was built in order to study the properties of high-density aerosol focusing for 1#22; m silica spheres. Preliminary results recover previous findings on aerodynamic focusing at low densities. At higher densities, it is demonstrated that the focusing properties change in a way which is consistent with a density dependent Stokes number.
Study of $^{64}$Ni+$^{132}$Sn Fusion with Density Constrained TDHF Formalism
A. S. Umar; V. E. Oberacker
2007-05-09T23:59:59.000Z
We study fusion reactions of the $^{64}$Ni+$^{132}$Sn system using the recently introduced density constrained time-dependent Hartree-Fock formalism. In this formalism the fusion barriers are directly obtained from TDHF dynamics. In addition, we incorporate the entrance channel alignment of the deformed (oblate) $^{64}$Ni nucleus due to dynamical Coulomb excitation. We discuss the influence of particle transfer and other dynamical effects on the fusion cross sections. Calculated cross sections are in very good agreement with data and other calculations.
Béal, M -P; Eilers, S; Perrin, D
2010-01-01T23:59:59.000Z
This chapter presents some of the links between automata theory and symbolic dynamics. The emphasis is on two particular points. The first one is the interplay between some particular classes of automata, such as local automata and results on embeddings of shifts of finite type. The second one is the connection between syntactic semigroups and the classification of sofic shifts up to conjugacy.
Statistical analysis of a dynamical multifragmentation path
A. H. Raduta; M. Colonna; V. Baran; M. Di Toro
2006-02-20T23:59:59.000Z
A microcanonical multifragmentation model (MMM) is used for investigating whether equilibration really occurs in the dynamical evolution of two heavy ion collisions simulated via a stochastic mean field approach (SMF). The standard deviation function between the dynamically obtained freeze-out fragment distributions corresponding to the reaction $^{129}$Xe+$^{119}$Sn at 32 MeV/u and the MMM ones corresponding to a wide range of mass, excitation energy, freeze-out volume and nuclear level density cut-off parameter shows a unique minimum. A distinct statistically equilibrated stage is identified in the dynamical evolution of the system.
Why quantum dynamics is linear
Thomas F. Jordan
2007-02-16T23:59:59.000Z
Quantum dynamics is linear. How do we know? From theory or experiment? The history of this question is reviewed. Nonlinear generalizations of quantum mechanics have been proposed. They predict small but clear nonlinear effects, which very accurate experiments have not seen. Is there a reason in principle why nonlinearity is not found? Is it impossible? Does quantum dynamics have to be linear? Attempts to prove this have not been decisive, because either their assumptions are not compelling or their arguments are not conclusive. The question has been left unsettled. There is a simple answer, based on a simple assumption. It was found in two steps separated by 44 years. They are steps back to simpler and more compelling assumptions. A proof of the assumptions of the Wigner-Bargmann proof has been known since 1962. It assumes that the maps of density matrices in time are linear. For this step, it is also assumed that density matrices are mapped one-to-one onto density matrices. An alternative is to assume that pure states are mapped one-to-one onto pure states and that entropy does not decrease. In a step taken in 2006, it is proved that the maps of density matrices in time are linear. It is assumed, as in the earlier step, that at each time the physical quantities and states are described by the usual linear structures of quantum mechanics, so the question is only about how things change in time. Beyond that, the proof assumes only that the dynamics does not depend on anything outside the system, but must allow the system to be described as part of a larger system.
Isomorphic classical molecular dynamics model for an excess electronin a supercritical fluid
Miller III, Thomas F.
2008-08-04T23:59:59.000Z
Ring polymer molecular dynamics (RPMD) is used to directly simulate the dynamics of an excess electron in a supercritical fluid over a broad range of densities. The accuracy of the RPMD model is tested against numerically exact path integral statistics through the use of analytical continuation techniques. At low fluid densities, the RPMD model substantially underestimates the contribution of delocalized states to the dynamics of the excess electron. However, with increasing solvent density, the RPMD model improves, nearly satisfying analytical continuation constraints at densities approaching those of typical liquids. In the high density regime, quantum dispersion substantially decreases the self-diffusion of the solvated electron. In this regime where the dynamics of the electron is strongly coupled to the dynamics of the atoms in the fluid, trajectories that can reveal diffusive motion of the electron are long in comparison to {beta}{h_bar}.
KH Computational Physics-2009 Density Functional Theory (DFT) Density Functional Theory
Haule, Kristjan
KH Computational Physics- 2009 Density Functional Theory (DFT) Density Functional Theory of interacting particles. Kristjan Haule, 2009 Â2Â #12;KH Computational Physics- 2009 Density Functional Theory functional of n. Kristjan Haule, 2009 Â3Â #12;KH Computational Physics- 2009 Density Functional Theory (DFT
Likos, Christos N.
Density-functional theory of nonuniform classical liquids: An extended modified weighted-density the approximationstreat long-rangeand short-rangepotentials. I. INTRODUCTION The density-functional theory of nonuniform of density- functional theory to the problem of freezing of classical liquids,4 and in particular
Population Density Population density (persons per square kilometer) layers, for 1990
Columbia University
Population Density Africa Population density (persons per square kilometer) layers, for 1990 the 12 population density classes. Source information: http://sedac.ciesin.columbia.edu/gpw/. Â´ Robinson://sedac.ciesin.columbia.edu/place/ Publish Date: 03/13/07 0 1,000 km Population Density 2000 0 Persons \\ Sq.Km 0-2 Persons \\ Sq.Km 2
Klippel, Alexander
Dot Density Maps Dot density maps, or dot maps, portray the geographic distribution of discrete for representing geographic patterns. Dot density maps are particularly useful for understanding global distribution of the mapped phenomenon and comparing relative densities of different regions on the map. Dot
Level dynamics and the ten-fold way
Alan T. Huckleberry; Marek Kus; Patrick Schuetzdeller
2007-02-25T23:59:59.000Z
We investigate the parameter dynamics of eigenvalues of Hamiltonians ('level dynamics') defined on symmetric spaces relevant for condensed matter and particle physics. In particular we: 1) identify appropriate reduced manifold on which the motion takes place, 2) identify the correct Poisson structure ensuring the Hamiltonian character of the reduced dynamics, 3) determine the canonical measure on the reduced space, 4) calculate the resulting eigenvalue density.
Michael Murray; for the BRAHMS Collaboration
2007-10-24T23:59:59.000Z
The purpose of BRAHMS is to survey the dynamics of relativistic heavy ion (as well as pp and d-A) collisions over a very wide range of rapidity and transverse momentum. The sum of these data may give us a glimpse of the initial state of the system, its transverse and longitudinal evolution and how the nature of the system changes with time. Here I will concentrate on the origin and dynamics of the light flavors, i.e. the creation and transport of the up, down and strange quarks. The results presented here are certainly not the end of the story. It is my hope that in a few years new detectors will reveal the rapidity dependence of the charm and bottom quarks.
Densities and viscosities of ternary ammonia/water fluids
Reiner, R.H.; Zaltash, A.
1993-03-01T23:59:59.000Z
The densities, viscosities, and boiling points (at barometric pressure) of solutions formed by inorganic salts dissolved in an ammonia/water (NH{sub 3}/H{sub 2}O) solvent have been measured. These ternary solutions of ammonia/water/dissolved salt are being investigated to reduce rectification requirements and to expand the temperature range of ammonia/water in advanced absorption cycles. Densities and viscosities of these fluids were measured over the temperature range of 283.15 to 343.15 K (10.0 to 70.0{degrees}C). Observed densities and viscosities were expressed as empirical functions of temperature by means of the least-squares method. The dynamic viscosities of ternary fluids were found to be three to seven times greater than those of the binary system of NH{sub 3}/H{sub 2}O, which implies that a substantial decrease in the film heat and mass transfer coefficient is possible. However, because this quantitative linkage is not well understood, direct measurements of heat and mass transfer rates in a minisorber are recommended and planned.
Quartz resonator fluid density and viscosity monitor
Martin, Stephen J. (Albuquerque, NM); Wiczer, James J. (Albuquerque, NM); Cernosek, Richard W. (Albuquerque, NM); Frye, Gregory C. (Cedar Crest, NM); Gebert, Charles T. (Albuquerque, NM); Casaus, Leonard (Bernalillo, NM); Mitchell, Mary A. (Tijeras, NM)
1998-01-01T23:59:59.000Z
A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.
Considering Air Density in Wind Power Production
Farkas, Zénó
2011-01-01T23:59:59.000Z
In the wind power production calculations the air density is usually considered as constant in time. Using the CIPM-2007 equation for the density of moist air as a function of air temperature, air pressure and relative humidity, we show that it is worth taking the variation of the air density into account, because higher accuracy can be obtained in the calculation of the power production for little effort.
Considering Air Density in Wind Power Production
Zénó Farkas
2011-03-11T23:59:59.000Z
In the wind power production calculations the air density is usually considered as constant in time. Using the CIPM-2007 equation for the density of moist air as a function of air temperature, air pressure and relative humidity, we show that it is worth taking the variation of the air density into account, because higher accuracy can be obtained in the calculation of the power production for little effort.
Method of synthesizing a low density material
Lorensen, L.E.; Monaco, S.B.
1987-02-27T23:59:59.000Z
A novel method of synthesizing a polymeric material of low density of the order of 50mg/cc or less. Such a low density material has applications in many areas including laser target fabrication. The method comprises preparing a polymer blend of two incompatible polymers as a major and a minor phase by mixing them and extruding the mixture, and then selectively extracting the major component, to yield a fine, low density structure.
Betatron radiation from density tailored plasmas
Ta Phuoc, Kim
2010-01-01T23:59:59.000Z
Betatron radiation from density tailored plasmas K. Tathe resulting betatron radiation spectrum can therefore bepro?le, the betatron radiation emitted by theses electrons
Some challenges for Nuclear Density Functional Theory
T. Duguet; K. Bennaceur; T. Lesinski; J. Meyer
2006-06-20T23:59:59.000Z
We discuss some of the challenges that the DFT community faces in its quest for the truly universal energy density functional applicable over the entire nuclear chart.
3-D capacitance density imaging system
Fasching, G.E.
1988-03-18T23:59:59.000Z
A three-dimensional capacitance density imaging of a gasified bed or the like in a containment vessel is achieved using a plurality of electrodes provided circumferentially about the bed in levels and along the bed in channels. The electrodes are individually and selectively excited electrically at each level to produce a plurality of current flux field patterns generated in the bed at each level. The current flux field patterns are suitably sensed and a density pattern of the bed at each level determined. By combining the determined density patterns at each level, a three-dimensional density image of the bed is achieved. 7 figs.
aerial density profiles: Topics by E-print Network
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
present an analytic approach to predict gas density and temperature profiles in dark matter haloes. We assume that the gas density profile traces the dark matter density profile...
Cui,Q.; Sulea, T.; Schrag, J.; Munger, C.; Hung, M.; Naim, M.; Cygler, M.; Purisima, E.
2008-01-01T23:59:59.000Z
Using the MP1-p14 scaffolding complex from the mitogen-activated protein kinase signaling pathway as model system, we explored a structure-based computational protocol to probe and characterize binding affinity hot spots at protein-protein interfaces. Hot spots are located by virtual alanine-scanning consensus predictions over three different energy functions and two different single-structure representations of the complex. Refined binding affinity predictions for select hot-spot mutations are carried out by applying first-principle methods such as the molecular mechanics generalized Born surface area (MM-GBSA) and solvated interaction energy (SIE) to the molecular dynamics (MD) trajectories for mutated and wild-type complexes. Here, predicted hot-spot residues were actually mutated to alanine, and crystal structures of the mutated complexes were determined. Two mutated MP1-p14 complexes were investigated, the p14(Y56A)-mutated complex and the MP1(L63A, L65A)-mutated complex. Alternative ways to generate MD ensembles for mutant complexes, not relying on crystal structures for mutated complexes, were also investigated. The SIE function, fitted on protein-ligand binding affinities, gave absolute binding affinity predictions in excellent agreement with experiment and outperformed standard MM-GBSA predictions when tested on the MD ensembles of Ras-Raf and Ras-RalGDS protein-protein complexes. For wild-type and mutant MP1-p14 complexes, SIE predictions of relative binding affinities were supported by a yeast two-hybrid assay that provided semiquantitative relative interaction strengths. Results on the MP1-mutated complex suggested that SIE predictions deteriorate if mutant MD ensembles are approximated by just mutating the wild-type MD trajectory. The SIE data on the p14-mutated complex indicated feasibility for generating mutant MD ensembles from mutated wild-type crystal structure, despite local structural differences observed upon mutation. For energetic considerations, this would circumvent costly needs to produce and crystallize mutated complexes. The sensitized protein-protein interface afforded by the p14(Y56A) mutation identified here has practical applications in screening-based discovery of first-generation small-molecule hits for further development into specific modulators of the mitogen-activated protein kinase signaling pathway.
Dynamic Positioning Simulator Dynamic Positioning Simulator
Vuik, Kees
Simulator 5 / 24 #12;Dynamic Positioning Simulator Dynamic Positioning Why Dynamic Positioning? Advantages Dynamic Positioning: No tugboats needed; Offshore set-up is quick; Power saving; Precision situations more on Ship: Wind Force Fw = 1 2 air V 2 rw CXw (rw )AT 1 2 air V 2 rw CYw (rw )AL Mw = 1 2 air V 2 rw CMw (rw
Li, Xiaolin [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China)] [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Ye, Li [Suzhou NeuPharma Co.,Ltd, Suzhou 215123 (China)] [Suzhou NeuPharma Co.,Ltd, Suzhou 215123 (China); Wang, Xiaoxiang [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China)] [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Wang, Xinzhou [Suzhou NeuPharma Co.,Ltd, Suzhou 215123 (China)] [Suzhou NeuPharma Co.,Ltd, Suzhou 215123 (China); Liu, Hongling [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China)] [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China); Zhu, Yongliang [Suzhou NeuPharma Co.,Ltd, Suzhou 215123 (China)] [Suzhou NeuPharma Co.,Ltd, Suzhou 215123 (China); Yu, Hongxia, E-mail: hongxiayu01@yahoo.com.cn [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China)] [State Key Laboratory of Pollution Control and Resource Reuse, School of the Environment, Nanjing University, Nanjing 210046 (China)
2012-12-15T23:59:59.000Z
Several recent reports suggested that hydroxylated polybrominated diphenyl ethers (HO-PBDEs) may disturb thyroid hormone homeostasis. To illuminate the structural features for thyroid hormone activity of HO-PBDEs and the binding mode between HO-PBDEs and thyroid hormone receptor (TR), the hormone activity of a series of HO-PBDEs to thyroid receptors ? was studied based on the combination of 3D-QSAR, molecular docking, and molecular dynamics (MD) methods. The ligand- and receptor-based 3D-QSAR models were obtained using Comparative Molecular Similarity Index Analysis (CoMSIA) method. The optimum CoMSIA model with region focusing yielded satisfactory statistical results: leave-one-out cross-validation correlation coefficient (q{sup 2}) was 0.571 and non-cross-validation correlation coefficient (r{sup 2}) was 0.951. Furthermore, the results of internal validation such as bootstrapping, leave-many-out cross-validation, and progressive scrambling as well as external validation indicated the rationality and good predictive ability of the best model. In addition, molecular docking elucidated the conformations of compounds and key amino acid residues at the docking pocket, MD simulation further determined the binding process and validated the rationality of docking results. -- Highlights: ? The thyroid hormone activities of HO-PBDEs were studied by 3D-QSAR. ? The binding modes between HO-PBDEs and TR? were explored. ? 3D-QSAR, molecular docking, and molecular dynamics (MD) methods were performed.
Theory for planetary exospheres: II. Radiation pressure effect on exospheric density profiles
Beth, Arnaud; Toublanc, Dominique; Dandouras, Iannis; Mazelle, Christian
2015-01-01T23:59:59.000Z
The planetary exospheres are poorly known in their outer parts, since the neutral densities are low compared with the instruments detection capabilities. The exospheric models are thus often the main source of information at such high altitudes. We present a new way to take into account analytically the additional effect of the radiation pressure on planetary exospheres. In a series of papers, we present with an Hamiltonian approach the effect of the radiation pressure on dynamical trajectories, density profiles and escaping thermal flux. Our work is a generalization of the study by Bishop and Chamberlain (1989). In this second part of our work, we present here the density profiles of atomic Hydrogen in planetary exospheres subject to the radiation pressure. We first provide the altitude profiles of ballistic particles (the dominant exospheric population in most cases), which exhibit strong asymmetries that explain the known geotail phenomenon at Earth. The radiation pressure strongly enhances the densities c...
Density waves in the shearing sheet IV. Interaction with a live dark halo
B. Fuchs
2004-03-01T23:59:59.000Z
It is shown that if the self-gravitating shearing sheet, a model of a patch of a galactic disk, is embedded in a live dark halo, this has a strong effect on the dynamics of density waves in the sheet. I describe how the density waves and the halo interact via halo particles either on orbits in resonance with the wave or on non-resonant orbits. Contrary to expectation the presence of the halo leads to a very considerable enhancement of the amplitudes of the density waves in the shearing sheet. This effect appears to be the equivalent of the recently reported enhanced growth of bars in numerically simulated stellar disks embedded in live dark halos. Finally I discuss the transfer of linear momentum from a density wave in the sheet to the halo and show that it is mediated only by halo particles on resonant orbits.
Nanoscale density fluctuations in swift heavy ion irradiated amorphous SiO{sub 2}
Kluth, P.; Giulian, R.; Ridgway, M. C. [Department of Electronic Materials Engineering, Australian National University, Canberra ACT 0200 (Australia); Pakarinen, O. H.; Djurabekova, F.; Nordlund, K. [Department of Physics and Helsinki Institute of Physics, University of Helsinki, Helsinki (Finland); Byrne, A. P. [Department of Nuclear Physics, Australian National University, Canberra ACT 0200 (Australia)
2011-12-15T23:59:59.000Z
We report on the observation of nanoscale density fluctuations in 2 {mu}m thick amorphous SiO{sub 2} layers irradiated with 185 MeV Au ions. At high fluences, in excess of approximately 5 x 10{sup 12} ions/cm{sup 2}, where the surface is completely covered by ion tracks, synchrotron small angle x-ray scattering measurements reveal the existence of a steady state of density fluctuations. In agreement with molecular dynamics simulations, this steady state is consistent with an ion track ''annihilation'' process, where high-density regions generated in the periphery of new tracks fill in low-density regions located at the center of existing tracks.
High density laser-driven target
Lindl, John D. (San Ramon, CA)
1981-01-01T23:59:59.000Z
A high density target for implosion by laser energy composed of a central quantity of fuel surrounded by a high-Z pusher shell with a low-Z ablator-pusher shell spaced therefrom forming a region filled with low-density material.
Density Estimation Trees in High Energy Physics
Anderlini, Lucio
2015-01-01T23:59:59.000Z
Density Estimation Trees can play an important role in exploratory data analysis for multidimensional, multi-modal data models of large samples. I briefly discuss the algorithm, a self-optimization technique based on kernel density estimation, and some applications in High Energy Physics.
Nuclear Dynamics at the Balance Energy
Aman D. Sood; Rajeev K. Puri
2003-11-05T23:59:59.000Z
We study the mass dependence of various quantities (like the average and maximum density, collision rate, participant-spectator matter, temperature as well as time zones for higher density) by simulating the reactions at the energy of vanishing flow. This study is carried out within the framework of Quantum Molecular Dynamics model. Our findings clearly indicate an existence of a power law in all the above quantities calculated at the balance energy. The only significant mass dependence was obtained for the temperature reached in the central sphere. All other quantities are rather either insensitive or depend weakly on the system size at balance energy. The time zone for higher density as well as the time of maximal density and collision rate follow a power law inverse to the energy of vanishing flow.
Density of Spray-Formed Materials
Kevin M. McHugh; Volker Uhlenwinkel; Nils Ellendr
2008-06-01T23:59:59.000Z
Spray Forming is an advanced materials processing technology that transforms molten metal into a near-net-shape solid by depositing atomized droplets onto a substrate. Depending on the application, the spray-formed material may be used in the as-deposited condition or it may undergo post-deposition processing. Regardless, the density of the as-deposited material is an important issue. Porosity is detrimental because it can significantly reduce strength, toughness, hardness and other properties. While it is not feasible to achieve fully-dense material in the as-deposited state, density greater than 99% of theoretical density is possible if the atomization and impact conditions are optimized. Thermal conditions at the deposit surface and droplet impact angle are key processing parameters that influence the density of the material. This paper examines the factors that contribute to porosity formation during spray forming and illustrates that very high as-deposited density is achieved by optimizing processing parameters.
Density functional theory for carbon dioxide crystal
Chang, Yiwen; Mi, Jianguo, E-mail: mijg@mail.buct.edu.cn; Zhong, Chongli [State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029 (China)
2014-05-28T23:59:59.000Z
We present a density functional approach to describe the solid?liquid phase transition, interfacial and crystal structure, and properties of polyatomic CO{sub 2}. Unlike previous phase field crystal model or density functional theory, which are derived from the second order direct correlation function, the present density functional approach is based on the fundamental measure theory for hard-sphere repulsion in solid. More importantly, the contributions of enthalpic interactions due to the dispersive attractions and of entropic interactions arising from the molecular architecture are integrated in the density functional model. Using the theoretical model, the predicted liquid and solid densities of CO{sub 2} at equilibrium triple point are in good agreement with the experimental values. Based on the structure of crystal-liquid interfaces in different planes, the corresponding interfacial tensions are predicted. Their respective accuracies need to be tested.
Neutral depletion and the helicon density limit
Magee, R. M.; Galante, M. E.; Carr, J. Jr.; Lusk, G.; McCarren, D. W.; Scime, E. E. [West Virginia University, Morgantown, West Virginia 26506 (United States)] [West Virginia University, Morgantown, West Virginia 26506 (United States)
2013-12-15T23:59:59.000Z
It is straightforward to create fully ionized plasmas with modest rf power in a helicon. It is difficult, however, to create plasmas with density >10{sup 20} m{sup ?3}, because neutral depletion leads to a lack of fuel. In order to address this density limit, we present fast (1 MHz), time-resolved measurements of the neutral density at and downstream from the rf antenna in krypton helicon plasmas. At the start of the discharge, the neutral density underneath the antenna is reduced to 1% of its initial value in 15 ?s. The ionization rate inferred from these data implies that the electron temperature near the antenna is much higher than the electron temperature measured downstream. Neutral density measurements made downstream from the antenna show much slower depletion, requiring 14 ms to decrease by a factor of 1/e. Furthermore, the downstream depletion appears to be due to neutral pumping rather than ionization.
How to Calculate Molecular Column Density
Mangum, Jeffrey G
2015-01-01T23:59:59.000Z
The calculation of the molecular column density from molecular spectral (rotational or ro-vibrational) transition measurements is one of the most basic quantities derived from molecular spectroscopy. Starting from first principles where we describe the basic physics behind the radiative and collisional excitation of molecules and the radiative transfer of their emission, we derive a general expression for the molecular column density. As the calculation of the molecular column density involves a knowledge of the molecular energy level degeneracies, rotational partition functions, dipole moment matrix elements, and line strengths, we include generalized derivations of these molecule-specific quantities. Given that approximations to the column density equation are often useful, we explore the optically thin, optically thick, and low-frequency limits to our derived general molecular column density relation. We also evaluate the limitations of the common assumption that the molecular excitation temperature is con...
Ions in solution: Density corrected density functional theory (DC-DFT)
Kim, Min-Cheol; Sim, Eunji, E-mail: esim@yonsei.ac.kr [Department of Chemistry and Institute of Nano-Bio Molecular Assemblies, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749 (Korea, Republic of)] [Department of Chemistry and Institute of Nano-Bio Molecular Assemblies, Yonsei University, 50 Yonsei-ro Seodaemun-gu, Seoul 120-749 (Korea, Republic of); Burke, Kieron [Department of Chemistry, University of California, Irvine, California 92697 (United States)] [Department of Chemistry, University of California, Irvine, California 92697 (United States)
2014-05-14T23:59:59.000Z
Standard density functional approximations often give questionable results for odd-electron radical complexes, with the error typically attributed to self-interaction. In density corrected density functional theory (DC-DFT), certain classes of density functional theory calculations are significantly improved by using densities more accurate than the self-consistent densities. We discuss how to identify such cases, and how DC-DFT applies more generally. To illustrate, we calculate potential energy surfaces of HO·Cl{sup ?} and HO·H{sub 2}O complexes using various common approximate functionals, with and without this density correction. Commonly used approximations yield wrongly shaped surfaces and/or incorrect minima when calculated self consistently, while yielding almost identical shapes and minima when density corrected. This improvement is retained even in the presence of implicit solvent.
The dynamics of fragment formation
Keane, D. [Kent State Univ., OH (United States); EOS Collaboration
1994-09-01T23:59:59.000Z
We demonstrate that in the Quantum Molecular Dynamics model, dynamical correlations can result in the production rate for final state nucleon clusters (and hence composite fragments) being higher than would be expected if statistics and the available phase space were dominant in determining composite formation. An intranuclear cascade or a Boltzmann-Uehling-Uhlenbeck model, combined with a statistical approach in the late stage of the collision to determine composites, provides an equivalent description only under limited conditions of centrality and beam energy. We use data on participant fragment production in Au + Au collisions in the Bevalac`s BOS time projection chamber to map out the parameter space where statistical clustering provides a good description. In particular, we investigate momentum-space densities of fragments up to {sup 4}He as a function of fragment transverse momentum, azimuth relative to the reaction plane, rapidity, multiplicity and beam energy.
Wood density measurement protocol J Chave Page 1 Measuring wood density for tropical forest trees
Chave, JÃ©rÃ´me
Wood density measurement protocol Â J Chave Page 1 Measuring wood density for tropical forest trees DiversitÃ© Biologique UniversitÃ© Paul Sabatier 31000 Toulouse, France 1. Introduction Wood is a biological, that transport the sap along the stem and they are filled by water. The density of tree wood is an interesting
Testing the kinetic energy functional: Kinetic energy density as a density functional
Burke, Kieron
is to the exchange-correlation energy as a functional of the density. A large part of the total energy, the kinetic contexts. For finite systems these forms integrate to the same global ki- netic energy, but they differTesting the kinetic energy functional: Kinetic energy density as a density functional Eunji Sim
GyPSuM: A Detailed Tomographic Model of Mantle Density and Seismic Wave Speeds
Simmons, N A; Forte, A M; Boschi, L; Grand, S P
2010-03-30T23:59:59.000Z
GyPSuM is a tomographic model fo mantle seismic shear wave (S) speeds, compressional wave (P) speeds and detailed density anomalies that drive mantle flow. the model is developed through simultaneous inversion of seismic body wave travel times (P and S) and geodynamic observations while considering realistic mineral physics parameters linking the relative behavior of mantle properties (wave speeds and density). Geodynamic observations include the (up to degree 16) global free-air gravity field, divergence of the tectonic plates, dynamic topography of the free surface, and the flow-induced excess ellipticity of the core-mantle boundary. GyPSuM is built with the philosophy that heterogeneity that most closely resembles thermal variations is the simplest possible solution. Models of the density field from Earth's free oscillations have provided great insight into the density configuration of the mantle; but are limited to very long-wavelength solutions. Alternatively, simply scaling higher resolution seismic images to density anomalies generates density fields that do not satisfy geodynamic observations. The current study provides detailed density structures in the mantle while directly satisfying geodynamic observations through a joint seismic-geodynamic inversion process. Notable density field observations include high-density piles at the base of the superplume structures, supporting the fundamental results of past normal mode studies. However, these features are more localized and lower amplitude than past studies would suggest. When we consider all seismic anomalies in GyPSuM, we find that P and S-wave speeds are strongly correlated throughout the mantle. However, correlations between the high-velocity S zones in the deep mantle ({approx} 2000 km depth) and corresponding P-wave anomalies are very low suggesting a systematic divergence from simplified thermal effects in ancient subducted slab anomalies. Nevertheless, they argue that temperature variations are the primary cause of P-wave, S-wave, and density anomalies in the mantle.
Liu, M.; Athar, A.; Zhu, Y.; Claridge, D. E.
1995-01-01T23:59:59.000Z
At the request of the Energy Management and Operations Department at M.D. Anderson Cancer Center, the Energy Systems Laboratory of Texas A&M University performed a study of optimizing the HVAC operation at its Basic Research Building. The Basic...
Periodic subsystem density-functional theory
Genova, Alessandro; Pavanello, Michele, E-mail: m.pavanello@rutgers.edu [Department of Chemistry, Rutgers University, Newark, New Jersey 07102 (United States); Ceresoli, Davide [Department of Chemistry, Rutgers University, Newark, New Jersey 07102 (United States); CNR-ISTM, Institute of Molecular Sciences and Technologies, Milano (Italy)
2014-11-07T23:59:59.000Z
By partitioning the electron density into subsystem contributions, the Frozen Density Embedding (FDE) formulation of subsystem Density Functional Theory (DFT) has recently emerged as a powerful tool for reducing the computational scaling of Kohn–Sham DFT. To date, however, FDE has been employed to molecular systems only. Periodic systems, such as metals, semiconductors, and other crystalline solids have been outside the applicability of FDE, mostly because of the lack of a periodic FDE implementation. To fill this gap, in this work we aim at extending FDE to treat subsystems of molecular and periodic character. This goal is achieved by a dual approach. On one side, the development of a theoretical framework for periodic subsystem DFT. On the other, the realization of the method into a parallel computer code. We find that periodic FDE is capable of reproducing total electron densities and (to a lesser extent) also interaction energies of molecular systems weakly interacting with metallic surfaces. In the pilot calculations considered, we find that FDE fails in those cases where there is appreciable density overlap between the subsystems. Conversely, we find FDE to be in semiquantitative agreement with Kohn–Sham DFT when the inter-subsystem density overlap is low. We also conclude that to make FDE a suitable method for describing molecular adsorption at surfaces, kinetic energy density functionals that go beyond the GGA level must be employed.
Density Prediction of Uranium-6 Niobium Ingots
D.F.Teter; P.K. Tubesing; D.J.Thoma; E.J.Peterson
2003-04-15T23:59:59.000Z
The densities of uranium-6 niobium (U-Nb) alloys have been compiled from a variety of literature sources such as Y-12 and Rocky Flats datasheets. We also took advantage of the 42 well-pedigreed, homogeneous baseline U-Nb alloys produced under the Enhanced Surveillance Program for density measurements. Even though U-Nb alloys undergo two-phase transitions as the Nb content varies from 0 wt. % to 8 wt %, the theoretical and measured densities vary linearly with Nb content. Therefore, the effect of Nb content on the density was modeled with a linear regression. From this linear regression, a homogeneous ingot of U-6 wt.% Nb would have a density of 17.382 {+-} 0.040 g/cc (95% CI). However, ingots produced at Y-12 are not homogeneous with respect to the Nb content. Therefore, using the 95% confidence intervals, the density of a Y-12 produced ingot would vary from 17.310 {+-} 0.043 g/cc at the center to 17.432 {+-} 0.039 g/cc at the edge. Ingots with larger Nb inhomogeneities will also have larger variances in the density.
Microscopic Description of Nuclear Fission Dynamics
A. S. Umar; V. E. Oberacker; J. A. Maruhn; P. -G. Reinhard
2010-03-22T23:59:59.000Z
We discuss possible avenues to study fission dynamics starting from a time-dependent mean-field approach. Previous attempts to study fission dynamics using the time-dependent Hartree-Fock (TDHF) theory are analyzed. We argue that different initial conditions may be needed to describe fission dynamics depending on the specifics of the fission phenomenon and propose various approaches towards this goal. In particular, we provide preliminary calculations for studying fission following a heavy-ion reaction using TDHF with a density contraint. Regarding prompt muon-induced fission, we also suggest a new approach for combining the time-evolution of the muonic wave function with a microscopic treatment of fission dynamics via TDHF.
Low density, resorcinol-formaldehyde aerogels
Pekala, R.W.
1988-05-26T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer ''clusters''. The covalent crosslinking of these ''clusters'' produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density less than or equal to100 mg/cc; cell size less than or equal to0.1 microns). The aerogels are transparent,dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 A/degree/. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron. 1 fig., 1 tab.
Low density, resorcinol-formaldehyde aerogels
Pekala, Richard W. (Pleasant Hill, CA)
1991-01-01T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "Clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density.ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100.circle.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.
Low density, resorcinol-formaldehyde aerogels
Pekala, Richard W. (Pleasant Hill, CA)
1989-01-01T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer "clusters". The covalent crosslinking of these "clusters" produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density .ltoreq.100 mg/cc; cell size .ltoreq.0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 .ANG.. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.
Low density, resorcinol-formaldehyde aerogels
Pekala, R.W.
1989-10-10T23:59:59.000Z
The polycondensation of resorcinol with formaldehyde under alkaline conditions results in the formation of surface functionalized polymer clusters. The covalent crosslinking of these clusters produces gels which when processed under supercritical conditions, produce low density, organic aerogels (density [<=]100 mg/cc; cell size [<=]0.1 microns). The aerogels are transparent, dark red in color and consist of interconnected colloidal-like particles with diameters of about 100 [angstrom]. These aerogels may be further carbonized to form low density carbon foams with cell size of about 0.1 micron.
The temperature dependence of equilibrium plasma density
B. V. Vasiliev
2002-03-17T23:59:59.000Z
Temperature dependence of an electron-nuclear plasma equilibrium density is considered basing on known approaches, which are given in (1)(2). It is shown that at a very high temperature, which is characteristic for a star interior, the equilibrium plasma density is almost constant and equals approximately to $10^{25}$ particles per $cm^3$. At a relatively low temperature, which is characteristic for star surface, the equilibrium plasma density is in several orders lower and depends on temperature as $T^{3/2}$.
Causes and consequences of complex population dynamics in an annual plant, Cardamine pensylvanica
Crone, E.E.
1995-11-08T23:59:59.000Z
The relative importance of density-dependent and density-independent factors in determining the population dynamics of plants has been widely debated with little resolution. In this thesis, the author explores the effects of density-dependent population regulation on population dynamics in Cardamine pensylvanica, an annual plant. In the first chapter, she shows that experimental populations of C. pensylvanica cycled from high to low density in controlled constant-environment conditions. These cycles could not be explained by external environmental changes or simple models of direct density dependence (N{sub t+1} = f[N{sub t}]), but they could be explained by delayed density dependence (N{sub t+1} = f[N{sub t}, N{sub t+1}]). In the second chapter, she shows that the difference in the stability properties of population growth models with and without delayed density dependence is due to the presence of Hopf as well as slip bifurcations from stable to chaotic population dynamics. She also measures delayed density dependence due to effects of parental density on offspring quality in C. pensylvanica and shows that this is large enough to be the cause of the population dynamics observed in C. pensylvanica. In the third chapter, the author extends her analyses of density-dependent population growth models to include interactions between competing species. In the final chapter, she compares the effects of fixed spatial environmental variation and variation in population size on the evolutionary response of C. pensylvanica populations.
Empirical vertical structure of density anomaly in the Gulf of Mexico
Current, Carole Louise
1993-01-01T23:59:59.000Z
) or Arango and Reid (1990b). Following custom in dealing with the dynamics of ocean circulation, we will treat the velocity (V) field as being nondivergent, (V V) = 0. The conservation of potential density is represented by the relation 1Dp ? =0 pDt (2... entering as a dependent variable, 8 84 +V? VB& =0 (2. 1. 4) and momentum equations, oV ? +V V?V+fkxV+V?b= F ot and given that ( is the upwardly positive rest state elevation of a potential density surface. Thus g is a function of p, and N (the Brunt...
Density Profiles of Liquid/Vapor Interfaces Away from Their Critical Point
Wei Bu; Doseok Kim; David Vaknin
2014-04-28T23:59:59.000Z
We examine the applicability of various model profiles for the liquid/vapor interface by X-ray reflectivities on water and ethanol and their mixtures at room temperature. Analysis of the X-ray reflecivities using various density profiles shows an error-function like profile is the most adequate within experimental error. Our finding, together with recent observations from simulation studies on liquid surfaces, strongly suggest that the capillary-wave dynamics shapes the interfacial density profile in terms of the error function.
Dynamics of colloidal particles in ice
Melissa Spannuth; S. G. J. Mochrie; S. S. L. Peppin; J. S. Wettlaufer
2010-12-31T23:59:59.000Z
We use X-ray Photon Correlation Spectroscopy (XPCS) to probe the dynamics of colloidal particles in polycrystalline ice. During freezing, the dendritic ice morphology and rejection of particles from the ice created regions of high-particle-density, where some of the colloids were forced into contact and formed disordered aggregates. We find that the particles in these high density regions underwent ballistic motion coupled with both stretched and compressed exponential decays of the intensity autocorrelation function, and that the particles' characteristic velocity increased with temperature. We explain this behavior in terms of ice grain boundary migration.
Shock compression of low-density foams
Holmes, N.C.
1993-07-01T23:59:59.000Z
Shock compression of very low density micro-cellular materials allows entirely new regimes of hot fluid states to be investigated experimentally. Using a two-stage light-gas gun to generate strong shocks, temperatures of several eV are readily achieved at densities of roughly 0.5--1 g/cm{sup 3} in large, uniform volumes. The conditions in these hot, expanded fluids are readily found using the Hugoniot jump conditions. We will briefly describe the basic methodology for sample preparation and experimental measurement of shock velocities. We present data for several materials over a range of initial densities. This paper will explore the applications of these methods for investigations of equations of state and phase diagrams, spectroscopy, and plasma physics. Finally, we discus the need for future work on these and related low-density materials.
Breast Density and Cancer | GE Global Research
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Breast Cancer Awareness Series: Understanding Breast Density Click to email this to a friend (Opens in new window) Share on Facebook (Opens in new window) Click to share (Opens in...
Magnetic fields and density functional theory
Salsbury Jr., Freddie
1999-02-01T23:59:59.000Z
A major focus of this dissertation is the development of functionals for the magnetic susceptibility and the chemical shielding within the context of magnetic field density functional theory (BDFT). These functionals depend on the electron density in the absence of the field, which is unlike any other treatment of these responses. There have been several advances made within this theory. The first of which is the development of local density functionals for chemical shieldings and magnetic susceptibilities. There are the first such functionals ever proposed. These parameters have been studied by constructing functionals for the current density and then using the Biot-Savart equations to obtain the responses. In order to examine the advantages and disadvantages of the local functionals, they were tested numerically on some small molecules.
Separation of carbon nanotubes in density gradients
Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)
2012-02-07T23:59:59.000Z
The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.
Density controlled carbon nanotube array electrodes
Ren, Zhifeng F. (Newton, MA); Tu, Yi (Belmont, MA)
2008-12-16T23:59:59.000Z
CNT materials comprising aligned carbon nanotubes (CNTs) with pre-determined site densities, catalyst substrate materials for obtaining them and methods for forming aligned CNTs with controllable densities on such catalyst substrate materials are described. The fabrication of films comprising site-density controlled vertically aligned CNT arrays of the invention with variable field emission characteristics, whereby the field emission properties of the films are controlled by independently varying the length of CNTs in the aligned array within the film or by independently varying inter-tubule spacing of the CNTs within the array (site density) are disclosed. The fabrication of microelectrode arrays (MEAs) formed utilizing the carbon nanotube material of the invention is also described.
Separation of carbon nanotubes in density gradients
Hersam, Mark C. (Evanston, IL); Stupp, Samuel I. (Chicago, IL); Arnold, Michael S. (Northbrook, IL)
2010-02-16T23:59:59.000Z
The separation of single-walled carbon nanotubes (SWNTs), by chirality and/or diameter, using centrifugation of compositions of SWNTs in and surface active components in density gradient media.
Inverse diffusion from knowledge of power densities
Bal, Guillaume; Monard, Francois; Triki, Faouzi
2011-01-01T23:59:59.000Z
This paper concerns the reconstruction of a diffusion coefficient in an elliptic equation from knowledge of several power densities. The power density is the product of the diffusion coefficient with the square of the modulus of the gradient of the elliptic solution. The derivation of such internal functionals comes from perturbing the medium of interest by acoustic (plane) waves, which results in small changes in the diffusion coefficient. After appropriate asymptotic expansions and (Fourier) transformation, this allow us to construct the power density of the equation point-wise inside the domain. Such a setting finds applications in ultrasound modulated electrical impedance tomography and ultrasound modulated optical tomography. We show that the diffusion coefficient can be uniquely and stably reconstructed from knowledge of a sufficient large number of power densities. Explicit expressions for the reconstruction of the diffusion coefficient are also provided. Such results hold for a large class of boundary...
High density effective theory on the lattice
A. Dougall
2007-10-08T23:59:59.000Z
Long-range interactions in finite density QCD necessitate a non-perturbative approach in order to reliably map out the key features and spectrum of the QCD phase diagram. However, the complex nature of the fermion determinant in this sector prohibits the use of established Monte Carlo techniques that utilize importance sampling. Whilst significant progress has been made in the low density, high temperature region, this remains a considerable challenge at mid to high density. At large chemical potential, QCD can be approximated using high density effective theory which is free from the sign problem at leading order. We investigate the implementation of this theory on the lattice in conjunction with existing re-weighting techniques.
Dynamic shape factors for hydox-generated plutonium dioxide-type non-sperical objects
Lohaus, James Harold
2012-06-07T23:59:59.000Z
. . . . . . . . . 1X NOMENCLATURE INTRODUCTION. BACKGROUND. THEORY. METHOD. . 14 Dynamic Shape Factors of a Hedron Characterized as a Single Variable, x. . Dynamic Shape Factors of a Hedron Characterized as Two Variables, x and y. Dynamic Shape Factors of a..., and this thesis to evaluates effects of the density and dynamic shape factors on the settling velocities of plutonium dioxide. THEORY Assume a particle in motion in a viscous fluid with velocity v. The fluid exerts a drag force on the particle defined as Fn...
QCD Level Density from Maximum Entropy Method
Shinji Ejiri; Tetsuo Hatsuda
2005-09-24T23:59:59.000Z
We propose a method to calculate the QCD level density directly from the thermodynamic quantities obtained by lattice QCD simulations with the use of the maximum entropy method (MEM). Understanding QCD thermodynamics from QCD spectral properties has its own importance. Also it has a close connection to phenomenological analyses of the lattice data as well as experimental data on the basis of hadronic resonances. Our feasibility study shows that the MEM can provide a useful tool to study QCD level density.
Cybersecurity Dynamics Shouhuai Xu
Xu, Shouhuai
Cybersecurity Dynamics Shouhuai Xu Department of Computer Science, University of Texas at San Antonio ABSTRACT We explore the emerging field of Cybersecurity Dynamics, a candidate foundation for the Science of Cybersecurity. Keywords Cybersecurity dynamics, security model, security analysis 1
Protein Dynamics and Biocatalysis
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Protein Dynamics and Biocatalysis Protein Dynamics and Biocatalysis 1998 Annual Report Grand Challenge Projects biocatalysis.gif A model of the Michaelis complex for the TEM-1...
Reduced density matrix hybrid approach: Application to electronic energy transfer
Berkelbach, Timothy C.; Reichman, David R. [Department of Chemistry, Columbia University, 3000 Broadway, New York, New York 10027 (United States); Markland, Thomas E. [Department of Chemistry, Stanford University, 333 Campus Drive, Stanford, California 94305 (United States)
2012-02-28T23:59:59.000Z
Electronic energy transfer in the condensed phase, such as that occurring in photosynthetic complexes, frequently occurs in regimes where the energy scales of the system and environment are similar. This situation provides a challenge to theoretical investigation since most approaches are accurate only when a certain energetic parameter is small compared to others in the problem. Here we show that in these difficult regimes, the Ehrenfest approach provides a good starting point for a dynamical description of the energy transfer process due to its ability to accurately treat coupling to slow environmental modes. To further improve on the accuracy of the Ehrenfest approach, we use our reduced density matrix hybrid framework to treat the faster environmental modes quantum mechanically, at the level of a perturbative master equation. This combined approach is shown to provide an efficient and quantitative description of electronic energy transfer in a model dimer and the Fenna-Matthews-Olson complex and is used to investigate the effect of environmental preparation on the resulting dynamics.
First Results of the LHC Longitudinal Density Monitor
Jeff, A.; /CERN /Liverpool U.; Boccardi, A.; /CERN; Bravin, E.; /CERN; Fisher, A.S.; /SLAC; Lefevre, T.; /CERN; Rabiller, A.; /CERN; Roncarolo, F.; /CERN; Welsch, C.P.; /Liverpool U. /Cockcroft Inst. Accel. Sci. Tech.
2012-04-19T23:59:59.000Z
The Large Hadron Collider (LHC) at CERN is the world's largest particle accelerator. It is designed to accelerate and collide protons or heavy ions up to the center-of-mass energies of 14 TeV. Knowledge of the longitudinal distribution of particles is important for various aspects of accelerator operation, in particular to check the injection quality and to measure the proportion of charge outside the nominally filled bunches during the physics periods. In order to study this so-called ghost charge at levels very much smaller than the main bunches, a longitudinal profile measurement with a very high dynamic range is needed. A new detector, the LHC Longitudinal Density Monitor (LDM) is a single-photon counting system measuring synchrotron light by means of an avalanche photodiode detector. The unprecedented energies reached in the LHC allow synchrotron light diagnostics to be used with both protons and heavy ions. A prototype was installed during the 2010 LHC run and was able to longitudinally profile the whole ring with a resolution close to the target of 50 ps. On-line correction for the effects of the detector deadtime, pile-up and afterpulsing allow a dynamic range of 105 to be achieved. First measurements with the LDM are presented here along with an analysis of its performance and an outlook for future upgrades.
Probability density adjoint for sensitivity analysis of the Mean of Chaos
Blonigan, Patrick J., E-mail: blonigan@mit.edu; Wang, Qiqi, E-mail: qiqi@mit.edu
2014-08-01T23:59:59.000Z
Sensitivity analysis, especially adjoint based sensitivity analysis, is a powerful tool for engineering design which allows for the efficient computation of sensitivities with respect to many parameters. However, these methods break down when used to compute sensitivities of long-time averaged quantities in chaotic dynamical systems. This paper presents a new method for sensitivity analysis of ergodic chaotic dynamical systems, the density adjoint method. The method involves solving the governing equations for the system's invariant measure and its adjoint on the system's attractor manifold rather than in phase-space. This new approach is derived for and demonstrated on one-dimensional chaotic maps and the three-dimensional Lorenz system. It is found that the density adjoint computes very finely detailed adjoint distributions and accurate sensitivities, but suffers from large computational costs.
Formation of droplets with high baryon density at the QCD phase transition in expanding matter
Christoph Herold; Marlene Nahrgang; Igor Mishustin; Marcus Bleicher
2014-07-22T23:59:59.000Z
We consider the (3+1) dimensional expansion and cooling of the chirally-restored and deconfined matter at finite net-baryon densities as expected in heavy-ion collisions at moderate energies. In our approach, we consider chiral fields and the Polyakov loop as dynamical variables coupled to a medium represented by a quark-antiquark fluid. The interaction between the fields and the fluid leads to dissipation and noise, which in turn affect the field fluctuations. We demonstrate how inhomogeneities in the net-baryon density may form during an evolution through the spinodal region of the first-order phase transition. For comparison, the dynamics of transition through the crossover and critical end point is also considered.
Nuclear energy density optimization: Shell structure
M. Kortelainen; J. McDonnell; W. Nazarewicz; E. Olsen; P. -G. Reinhard; J. Sarich; N. Schunck; S. M. Wild; D. Davesne; J. Erler; A. Pastore
2014-04-28T23:59:59.000Z
Nuclear density functional theory is the only microscopical theory that can be applied throughout the entire nuclear landscape. Its key ingredient is the energy density functional. In this work, we propose a new parameterization UNEDF2 of the Skyrme energy density functional. The functional optimization is carried out using the POUNDerS optimization algorithm within the framework of the Skyrme Hartree-Fock-Bogoliubov theory. Compared to the previous parameterization UNEDF1, restrictions on the tensor term of the energy density have been lifted, yielding a very general form of the energy density functional up to second order in derivatives of the one-body density matrix. In order to impose constraints on all the parameters of the functional, selected data on single-particle splittings in spherical doubly-magic nuclei have been included into the experimental dataset. The agreement with both bulk and spectroscopic nuclear properties achieved by the resulting UNEDF2 parameterization is comparable with UNEDF1. While there is a small improvement on single-particle spectra and binding energies of closed shell nuclei, the reproduction of fission barriers and fission isomer excitation energies has degraded. As compared to previous UNEDF parameterizations, the parameter confidence interval for UNEDF2 is narrower. In particular, our results overlap well with those obtained in previous systematic studies of the spin-orbit and tensor terms. UNEDF2 can be viewed as an all-around Skyrme EDF that performs reasonably well for both global nuclear properties and shell structure. However, after adding new data aiming to better constrain the nuclear functional, its quality has improved only marginally. These results suggest that the standard Skyrme energy density has reached its limits and significant changes to the form of the functional are needed.
Dynamical properties of superconducting nanowires
Nikolaev, S. V.; Yugay, K. N. [Omsk State University (Russian Federation)], E-mail: yugay_klimenty@mail.ru
2006-02-15T23:59:59.000Z
The dynamical properties of thin superconducting wires (nanowires) are studied using numerical simulations based on a one-dimensional time-dependent Ginzburg-Landau equation, which is modified by introducing an order parameter u characterizing the 'purity' of the superconductor material. It is established that relatively long nanowires (with lengths much greater than the coherence length) made of a 'pure' superconductor (u > 1) are characterized by two critical current density values: j{sub c1} and j{sub c2}. For j < j{sub c1}, the total current is entirely superconducting, whereas for j > j{sub c2}, the current is purely normal. In the intermediate region of current densities, j{sub c1} < j < j{sub c2}, the total current contains both superconducting and normal components (mixed state) and the nanowire exhibits the generation of high-frequency electromagnetic waves. The current-voltage characteristics are constructed and the radiation spectrum is obtained. The properties of short superconducting nanowires (with lengths on the order of the coherence length) coincide with those of the Josephson junction. In the case of an 'impure' superconductor (u < 1), the nanowire is characterized by a single critical current density.
Zheltikov, A. M.; Voronin, A. A. [Department of Physics, International Laser Center, M.V. Lomonosov Moscow State University, Moscow 119992 (Russian Federation); Shneider, M. N.; Miles, R. B. [Department of Mechanical and Aerospace Engineering, Princeton University, Princeton, New Jersey 08544-5263 (United States)
2011-02-01T23:59:59.000Z
Enhancement of multiphonon tunneling recombination of free carriers in strong laser fields is shown to offer a mechanism whereby ultrafast carrier-density dynamics in a semiconductor can be controlled by properly shaped laser pulses. This regime of laser-solid interaction enables an ultrafast switching of optical and electric properties of semiconductor materials, suggesting new strategies for laser micromachining and nanomachining, optical data processing, and ultrafast plasmonics.
A Bayesian Probability Calculus for Density Matrices
Manfred K. Warmuth; Dima Kuzmin
2014-08-09T23:59:59.000Z
One of the main concepts in quantum physics is a density matrix, which is a symmetric positive definite matrix of trace one. Finite probability distributions are a special case where the density matrix is restricted to be diagonal. Density matrices are mixtures of dyads, where a dyad has the form uu' for any any unit column vector u. These unit vectors are the elementary events of the generalized probability space. Perhaps the simplest case to see that something unusual is going on is the case of uniform density matrix, i.e. 1/n times identity. This matrix assigns probability 1/n to every unit vector, but of course there are infinitely many of them. The new normalization rule thus says that sum of probabilities over any orthonormal basis of directions is one. We develop a probability calculus based on these more general distributions that includes definitions of joints, conditionals and formulas that relate these, i.e. analogs of the theorem of total probability, various Bayes rules for the calculation of posterior density matrices, etc. The resulting calculus parallels the familiar 'classical' probability calculus and always retains the latter as a special case when all matrices are diagonal. Whereas the classical Bayesian methods maintain uncertainty about which model is 'best', the generalization maintains uncertainty about which unit direction has the largest variance. Surprisingly the bounds also generalize: as in the classical setting we bound the negative log likelihood of the data by the negative log likelihood of the MAP estimator.
Tracing spiral density waves in M81
S. Kendall; R. C. Kennicutt; C. Clarke; M. D. Thornley
2008-04-15T23:59:59.000Z
We use SPITZER IRAC 3.6 and 4.5micron near infrared data from the Spitzer Infrared Nearby Galaxies Survey (SINGS), optical B, V and I and 2MASS Ks band data to produce mass surface density maps of M81. The IRAC 3.6 and 4.5micron data, whilst dominated by emission from old stellar populations, is corrected for small-scale contamination by young stars and PAH emission. The I band data are used to produce a mass surface density map by a B-V colour-correction, following the method of Bell and de Jong. We fit a bulge and exponential disc to each mass map, and subtract these components to reveal the non-axisymmetric mass surface density. From the residual mass maps we are able to extract the amplitude and phase of the density wave, using azimuthal profiles. The response of the gas is observed via dust emission in the 8micron IRAC band, allowing a comparison between the phase of the stellar density wave and gas shock. The relationship between this angular offset and radius suggests that the spiral structure is reasonably long lived and allows the position of corotation to be determined.
ORBITAL-FREE KINETIC-ENERGY DENSITY FUNCTIONAL THEORY
Wang, Yan Alexander
Chapter 5 ORBITAL-FREE KINETIC-ENERGY DENSITY FUNCTIONAL THEORY Yan Alexander Wang and Emily A Theory (DFT), there was the Thomas-Fermi (TF) model, which uses the electron density Â¢Â¡ rÂ£ (a function-dependent DFT Density-Functional Theory DI density-independent DM1 first-order reduced density matrix EDF energy
White noise approach to the low density limit of a quantum particle in a gas
Alexander Pechen
2006-07-19T23:59:59.000Z
The white noise approach to the investigation of the dynamics of a quantum particle interacting with a dilute and in general non-equilibrium gaseous environment in the low density limit is outlined. The low density limit is the kinetic Markovian regime when only pair collisions (i.e., collisions of the test particle with one particle of the gas at one time moment) contribute to the dynamics. In the white noise approach one first proves that the appropriate operators describing the gas converge in the sense of appropriate matrix elements to certain operators of quantum white noise. Then these white noise operators are used to derive quantum white noise and quantum stochastic equations describing the approximate dynamics of the total system consisting of the particle and the gas. The derivation is given ab initio, starting from the exact microscopic quantum dynamics. The limiting dynamics is described by a quantum stochastic equation driven by a quantum Poisson process. This equation then applied to the derivation of quantum Langevin equation and linear Boltzmann equation for the reduced density matrix of the test particle. The first part of the paper describes the approach which was developed by L. Accardi, I.V. Volovich and the author and uses the Fock-antiFock (or GNS) representation for the CCR algebra of the gas. The second part presents the approach to the derivation of the limiting equations directly in terms of the correlation functions, without use of the Fock-antiFock representation. This approach simplifies the derivation and allows to express the strength of the quantum number process directly in terms of the one-particle $S$-matrix.
High power density solid oxide fuel cells
Pham, Ai Quoc; Glass, Robert S.
2004-10-12T23:59:59.000Z
A method for producing ultra-high power density solid oxide fuel cells (SOFCs). The method involves the formation of a multilayer structure cells wherein a buffer layer of doped-ceria is deposited intermediate a zirconia electrolyte and a cobalt iron based electrode using a colloidal spray deposition (CSD) technique. For example, a cobalt iron based cathode composed of (La,Sr)(Co,Fe)O (LSCF) may be deposited on a zirconia electrolyte via a buffer layer of doped-ceria deposited by the CSD technique. The thus formed SOFC have a power density of 1400 mW/cm.sup.2 at 600.degree. C. and 900 mW/cm.sup.2 at 700.degree. C. which constitutes a 2-3 times increased in power density over conventionally produced SOFCs.
Statistical approach to nuclear level density
Sen'kov, R. A.; Horoi, M. [Department of Physics, Central Michigan University, Mount Pleasant, MI 48859 (United States); Zelevinsky, V. G. [Department of Physics and Astronomy and National Superconducting Cyclotron Laboratory, Michigan State University, East Lansing, MI 48824-1321 (United States)
2014-10-15T23:59:59.000Z
We discuss the level density in a finite many-body system with strong interaction between the constituents. Our primary object of applications is the atomic nucleus but the same techniques can be applied to other mesoscopic systems. We calculate and compare nuclear level densities for given quantum numbers obtained by different methods, such as nuclear shell model (the most successful microscopic approach), our main instrument - moments method (statistical approach), and Fermi-gas model; the calculation with the moments method can use any shell-model Hamiltonian excluding the spurious states of the center-of-mass motion. Our goal is to investigate statistical properties of nuclear level density, define its phenomenological parameters, and offer an affordable and reliable way of calculation.
Neutron Matter from Low to High Density
Gandolfi, Stefano; Carlson, J
2015-01-01T23:59:59.000Z
Neutron matter is an intriguing nuclear system with multiple connections to other areas of physics. Considerable progress has been made over the last two decades in exploring the properties of pure neutron fluids. Here we begin by reviewing work done to explore the behavior of very low density neutron matter, which forms a strongly paired superfluid and is thus similar to cold Fermi atoms, though at energy scales differing by many orders of magnitude. We then increase the density, discussing work that ties the study of neutron matter with the determination of the properties of neutron-rich nuclei and neutron-star crusts. After this, we review the impact neutron matter at even higher densities has on the mass-radius relation of neutron stars, thereby making contact with astrophysical observations.
Fabrication of low density ceramic material
Meek, T.T.; Blake, R.D.; Sheinberg, H.
1985-01-01T23:59:59.000Z
A precursor mixture and a method of making a low-density ceramic structural material are disclosed. The precursor mixture includes hollow microballoons, typically made of glass, together with a cementing agent capable of being cured by microwave irradiation. A preferred cementing agent is liquid hydrated potassium silicate, which is mixed with the glass microballoons to form a slurry. Upon irradiation the potassium silicate is dehydrated to form a solid porous matrix in which the microballoons are evenly distributed. Ground glass or other filling agents may be included in the slurry to enhance the properties of the final product. Low-density structural ceramics having densities on the order of 0.1 to 0.3 are obtained.
Leonard, T.; Lander, B.; Seifert, U. [II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart (Germany)] [II. Institut für Theoretische Physik, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart (Germany); Speck, T. [Institut für Theoretische Physik II, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf (Germany)] [Institut für Theoretische Physik II, Heinrich-Heine-Universität Düsseldorf, Universitätsstraße 1, 40225 Düsseldorf (Germany)
2013-11-28T23:59:59.000Z
We discuss the stochastic thermodynamics of systems that are described by a time-dependent density field, for example, simple liquids and colloidal suspensions. For a time-dependent change of external parameters, we show that the Jarzynski relation connecting work with the change of free energy holds if the time evolution of the density follows the Kawasaki-Dean equation. Specifically, we study the work distributions for the compression and expansion of a two-dimensional colloidal model suspension implementing a practical coarse-graining scheme of the microscopic particle positions. We demonstrate that even if coarse-grained dynamics and density functional do not match, the fluctuation relations for the work still hold albeit for a different, apparent, change of free energy.
Density matrix of black hole radiation
Lasma Alberte; Ram Brustein; Andrei Khmelnitsky; A. J. M. Medved
2015-02-09T23:59:59.000Z
Hawking's model of black hole evaporation is not unitary and leads to a mixed density matrix for the emitted radiation, while the Page model describes a unitary evaporation process in which the density matrix evolves from an almost thermal state to a pure state. We compare a recently proposed model of semiclassical black hole evaporation to the two established models. In particular, we study the density matrix of the outgoing radiation and determine how the magnitude of the off-diagonal corrections differs for the three frameworks. For Hawking's model, we find power-law corrections to the two-point functions that induce exponentially suppressed corrections to the off-diagonal elements of the full density matrix. This verifies that the Hawking result is correct to all orders in perturbation theory and also allows one to express the full density matrix in terms of the single-particle density matrix. We then consider the semiclassical theory for which the corrections, being non-perturbative from an effective field-theory perspective, are much less suppressed and grow monotonically in time. In this case, the R\\'enyi entropy for the outgoing radiation is shown to grow linearly at early times; but this growth slows down and the entropy eventually starts to decrease at the Page time. In addition to comparing models, we emphasize the distinction between the state of the radiation emitted from a black hole, which is highly quantum, and that of the radiation emitted from a typical classical black body at the same temperature.
E-Cloud Effects on Singe-Bunch Dynamics in the Proposed PS2
Venturini, M.
2012-01-01T23:59:59.000Z
E-CLOUD EFFECTS ON SINGLE-BUNCH DYNAMICS IN THE PROPOSEDsynchrotron. Electron cloud effects represent an impor- tantaiming at estimating the e-cloud density thresholds for the
Molecular Dynamics Simulation of the Transport Properties of Molten Transuranic Chloride Salts
Baty, Austin Alan
2013-02-06T23:59:59.000Z
are critical to modeling both the neutronics and heat transfer of an ADSMS system. There is a lack of experimental data on the density, heat capacity, electrical and thermal conductivities, and viscosity of TRUCl3 salt systems. Molecular dynamics simulations...
Accelerated molecular dynamics methods
Perez, Danny [Los Alamos National Laboratory
2011-01-04T23:59:59.000Z
The molecular dynamics method, although extremely powerful for materials simulations, is limited to times scales of roughly one microsecond or less. On longer time scales, dynamical evolution typically consists of infrequent events, which are usually activated processes. This course is focused on understanding infrequent-event dynamics, on methods for characterizing infrequent-event mechanisms and rate constants, and on methods for simulating long time scales in infrequent-event systems, emphasizing the recently developed accelerated molecular dynamics methods (hyperdynamics, parallel replica dynamics, and temperature accelerated dynamics). Some familiarity with basic statistical mechanics and molecular dynamics methods will be assumed.
Configuration Interactions Constrained by Energy Density Functionals
B. Alex Brown; Angelo Signoracci; Morten Hjorth-Jensen
2010-09-24T23:59:59.000Z
A new method for constructing a Hamiltonian for configuration interaction calculations with constraints to energies of spherical configurations obtained with energy-density-functional (EDF) methods is presented. This results in a unified model that reproduced the EDF binding-energy in the limit of single-Slater determinants, but can also be used for obtaining energy spectra and correlation energies with renormalized nucleon-nucleon interactions. The three-body and/or density-dependent terms that are necessary for good nuclear saturation properties are contained in the EDF. Applications to binding energies and spectra of nuclei in the region above 208Pb are given.
Josephson oscillations of charge density waves
Ruvalds, J.; Tua, P.F.
1985-01-01T23:59:59.000Z
The formation of charge density waves in solids was originally proposed as a possible mechanism for superconductivity by Froehlich. Although the experimentally discovered materials with charge density waves (CDW)s are found to have finite resistivity as a result of impurity pinning, they nevertheless reveal many interesting features including motion which is analogous to a resistively shunted Josephson junction of superconductors. The noise spectrum of CDW systems is reviewed with particular emphasis on interactions with normal as well as magnetic impurities. Future prospects for observing an amplitude variation of the noise signals induced by a magnetic field are proposed.
Error Analysis in Nuclear Density Functional Theory
Nicolas Schunck; Jordan D. McDonnell; Jason Sarich; Stefan M. Wild; Dave Higdon
2014-07-11T23:59:59.000Z
Nuclear density functional theory (DFT) is the only microscopic, global approach to the structure of atomic nuclei. It is used in numerous applications, from determining the limits of stability to gaining a deep understanding of the formation of elements in the universe or the mechanisms that power stars and reactors. The predictive power of the theory depends on the amount of physics embedded in the energy density functional as well as on efficient ways to determine a small number of free parameters and solve the DFT equations. In this article, we discuss the various sources of uncertainties and errors encountered in DFT and possible methods to quantify these uncertainties in a rigorous manner.
Low density, microcellular foams, preparation, and articles
Young, A.T.
1982-03-03T23:59:59.000Z
A microcellular low-density foam of poly(4-methyl-1-pentene) particularly useful for forming targets for inertial confinement fusion has been developed. Articles made from the foam have been machined to tolerances of 0.0001 inch, although the densities of the fragile foam are low (about 10 to about 100 mg/cc) and the cell sizes are small (about 10 to about 30 ..mu..m). Methods for forming the foam and articles are given. The yield strength of the foam of the invention is higher than was obtained in other structures of this same material.
Chen, Guo [Los Alamos National Laboratory; Mcmahon, Benjamin H [Los Alamos National Laboratory; Tung, Chang - Shung [Los Alamos National Laboratory
2008-01-01T23:59:59.000Z
Phosphorylation-activated modulation of response regulators (RR) is predominantly used by bacteria as a strategy in regulating their two-component signaling (TCS) systems, the underlying molecular mechanisms are however far from fully understood. In this work we have conducted a molecular dynamics (MD) simulation of the phosphorylation-induced conformational transitions of RRs with the Mycobacterium Tuberculosis PrrA as a particular example. Starting from the full-length inactive structure of PrrA we introduced a local disturbance by phosphorylating the conserved aspartic acid residue, Asp-58, in the regulatory domain. A Go-model-type algorithm packaged with AMBER force fields was then applied to simulate the dynamics upon phosphorylation. The MD simulation shows that the phosphorylation of Asp-58 facilitates PrrA, whose inactive state has a compact conformation with a closed interdomain interface, to open up with its interdomain separation being increased by an average of about 1.5 {angstrom} for a simulation of 20 ns. The trans-activation loop, which is completely buried within the interdomain interface in the inactive PrrA, is found to become more exposed with the phosphorylated structure as well. These results provide more structural details of how the phosphorylation of a local aspartate activates PrrA to undergo a global conformational rearrangement toward its extended active state. This work also indicates that MD simulations can serve as a fast tool to unravel the regulation mechanisms of all RRs, which is especially valuable when the structures of full-length active RRs are currently unavailable.
Harilal, S. S.
-produced plasma (LPP) for various applications should consider details of spatial and temporal input power de in hydro- dynamic evolution of the produced plasma sources. Index Terms--CO2 laser, critical density and optimization of radiation sources for the next generation of nanolithography, i.e., the extreme ultravi- olet
Sergey Yakovlev
2011-12-22T23:59:59.000Z
In the work's considered density of vacuum energy and dynamic of scalar field in multidimensional theory with cosmological constant. Using method of N.N.Bogolubov coefficients, was gotten expression for influence of anisotropic metric to vacuum energy. Obtained the effective mass of massles scalar field, that depends on cosmological constant, and some general theoretical results concerning arising of particles in the model.
Time Dependent Density Functional Theory Application to Extended Systems
Botti, Silvana
Time Dependent Density Functional Theory Application to Extended Systems Francesco Sottile Facility (ETSF) Donostia, 25 July 2007 Time Dependent Density Functional Theory Francesco Sottile #12 Density Functional Theory Francesco Sottile #12;Linear Periodic systems ALDA The Quest for the Holy
Mechanical constraints enhance electrical energy densities of soft dielectrics
Ferrari, Silvia
Mechanical constraints enhance electrical energy densities of soft dielectrics Lin Zhang, Qiming, the dielectric will breakdown electrically. The breakdown limits the electrical energy density of the dielectric electric fields and thus increase their electrical energy densities. The mechanical constraints suppress
neutron density. The neutron density (nn) of the source was modeled by solving the simul-
West, Stuart
neutron density. The neutron density (nn) of the source was modeled by solving the simul- taneousT is the thermal neutron velocity, l is the decay constant, Ns is the s-process abun- dance, bsÃ? is the maxwellian-averaged neutron capture cross-section, and t0 is the average neutron exposure (21). The branching decay of 186Re
On the Determination of the Mean Cosmic Matter Density and the Amplitude of Density Fluctuations
Thomas H. Reiprich
2002-07-02T23:59:59.000Z
The cosmological implications from a new estimate of the local X-ray galaxy cluster abundance are summarized. The results are then compared to independent observations. It is suggested that `low' values for the mean cosmic matter density and the amplitude of mass density fluctuations currently do not appear unreasonable observationally.
Theoretical Electron Density Distributions for Fe- and Cu-Sulfide...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Electron Density Distributions for Fe- and Cu-Sulfide Earth Materials: A Connection between Bond Length, Bond Theoretical Electron Density Distributions for Fe- and Cu-Sulfide...
High power density supercapacitors using locally aligned carbon nanotube electrodes
Du, C S; Yeh, J; Pan, Ning
2005-01-01T23:59:59.000Z
High power density supercapacitors using locally alignedof high power density supercapacitors and other similarcells [6], and for supercapacitors [7–18]. As unique energy
Novel and Optimized Materials Phases for High Energy Density...
Broader source: Energy.gov (indexed) [DOE]
Novel and Optimized Materials Phases for High Energy Density Batteries Novel and Optimized Materials Phases for High Energy Density Batteries 2013 DOE Hydrogen and Fuel Cells...
TEMPO-based Catholyte for High Energy Density Nonaqueous Redox...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
TEMPO-based Catholyte for High Energy Density Nonaqueous Redox Flow Batteries. TEMPO-based Catholyte for High Energy Density Nonaqueous Redox Flow Batteries. Abstract: We will...
High Energy Density Laboratory Plasmas Program | National Nuclear...
National Nuclear Security Administration (NNSA)
Photo Gallery Jobs Apply for Our Jobs Our Jobs Working at NNSA Blog Home High Energy Density Laboratory Plasmas Program High Energy Density Laboratory Plasmas Program...
Estimating density of Florida Key deer
Roberts, Clay Walton
2006-08-16T23:59:59.000Z
for this species since 1968; however, a need to evaluate the precision of existing and alternative survey methods (i.e., road counts, mark-recapture, infrared-triggered cameras [ITC]) was desired by USFWS. I evaluated density estimates from unbaited ITCs and road...
RICE UNIVERSITY Screened Coulomb Hybrid Density Functionals
Scuseria, Gustavo E.
in Partial Fulfillment of the Requirements for the Degree Doctor of Philosophy Approved, Thesis Committee-Scuseria-Ernzerhof (HSE) screened Coulomb hybrid density functional is designed to produce exchange energies comparable to traditional hybrids while only using the short range, screened HF exchange. #12;The accuracy of the HSE
THE QCD PHASE DIAGRAM AT FINITE DENSITY.
SCHMIDT, C.; FODOR, Z.; KATZ, S.
2005-07-25T23:59:59.000Z
We study the density of states method to explore the phase diagram of the chiral transition on the temperature and quark chemical potential plane. Four quark flavours are used in the analysis. Though the method is quite expensive small lattices show an indication for a triple-point connecting three different phases on the phase diagram.
Density Functional Theory Approach to Nuclear Fission
N. Schunck
2013-01-20T23:59:59.000Z
The Skyrme nuclear energy density functional theory (DFT) is used to model neutron-induced fission in actinides. This paper focuses on the numerical implementation of the theory. In particular, it reports recent advances in DFT code development on leadership class computers, and presents a detailed analysis of the numerical accuracy of DFT solvers for near-scission calculations.
Modern applications of covariant density functional theory
P. Ring; H. Abusara; A. V. Afanasjev; G. A. Lalazissis; T. Niksic; D. Vretenar
2011-09-19T23:59:59.000Z
Modern applications of Covariant Density Functional Theory (CDFT) are discussed. First we show a systematic investigation of fission barriers in actinide nuclei within constraint relativistic mean field theory allowing for triaxial deformations. In the second part we discuss a microscopic theory of quantum phase transitions (QPT) based on the relativistic generator coordinate method.
Drawing Electron Density Maps Tutorial : J. Reibenspies
Meagher, Mary
file Choose the difference map #12;Step 2 Â· If necessary generate full molecule in XSEED or XP shift key to pan) #12;Step 4 Â· All ball and stick plot to spice it up ZOOMED #12;Step 5 Â· Save screen the electron density in the macocyclic void in order to understand the disorder #12;Step one Â· In the INS
Density waves in the Calogero model - revisited
Bardek, V. [Rudjer Boskovic Institute, Bijenicka c.54, HR-10002 Zagreb (Croatia)], E-mail: bardek@irb.hr; Feinberg, J. [Department of Physics, University of Haifa at Oranim, Tivon 36006 (Israel); Department of Physics, Technion-Israel Inst. of Technology, Haifa 32000 (Israel); KITP, University of California, Santa Barbara, CA 93106-4030 (United States)], E-mail: joshua@physics.technion.ac.il; Meljanac, S. [Rudjer Boskovic Institute, Bijenicka c.54, HR-10002 Zagreb (Croatia)], E-mail: meljanac@irb.hr
2010-03-15T23:59:59.000Z
The Calogero model bears, in the continuum limit, collective excitations in the form of density waves and solitary modulations of the density of particles. This sector of the spectrum of the model was investigated, mostly within the framework of collective-field theory, by several authors, over the past 15 years or so. In this work we shall concentrate on periodic solutions of the collective BPS-equation (also known as 'finite amplitude density waves'), as well as on periodic solutions of the full static variational equations which vanish periodically (also known as 'large amplitude density waves'). While these solutions are not new, we feel that our analysis and presentation add to the existing literature, as we explain in the text. In addition, we show that these solutions also occur in a certain two-family generalization of the Calogero model, at special points in parameter space. A compendium of useful identities associated with Hilbert transforms, including our own proofs of these identities, appears in Appendix A. In Appendix B we also elucidate in the present paper some fine points having to do with manipulating Hilbert-transforms, which appear ubiquitously in the collective field formalism. Finally, in order to make this paper self-contained, we briefly summarize in Appendix C basic facts about the collective field formulation of the Calogero model.
Photovoltaic retinal prosthesis with high pixel density
Palanker, Daniel
Photovoltaic retinal prosthesis with high pixel density Keith Mathieson1,4 , James Loudin1 to stimulating electrodes via intraocular cables. We present a photovoltaic subretinal prosthesis, in which pixel, demonstrating the possibility of a fully integrated photovoltaic retinal prosthesis with high
Master's Thesis Density Functional Theory for
Armiento, Rickard
of the information found during my work. v #12;vi #12;Contents Abstract #12;Abstract This thesis presents a number of results for basic quantum mechanical models intended to be used in the development of density functional theory for systems with edges. Following previous work
Methods to enhance blanket power density
Hsu, P.Y.; Miller, L.G.; Bohn, T.S.; Deis, G.A.; Longhurst, G.R.; Masson, L.S.; Wessol, D.E.; Abdou, M.A.
1982-06-01T23:59:59.000Z
The overall objective of this task is to investigate the extent to which the power density in the FED/INTOR breeder blanket test modules can be enhanced by artificial means. Assuming a viable approach can be developed, it will allow advanced reactor blanket modules to be tested on FED/INTOR under representative conditions.
'\\'1' TI,l, lES '1'1 IF DFSERT O\\N \\ L\\Jpipe in the dirt many times ,md tl)und it exciting.'"
JF.NTIAL a pipe in the dirt many times ,md tl)und it exciting.'" and even foolish. Bill Schlesinger feels th~1t gn)wth wit.h 'I rock hammer and a metal pipe, She drives the pipe two inches into tlle gnl all d,e plant li the hlows ringing out in tllC silence. Then shpipe out and t
Goldman, Steven A.
Heart DiseaseHeart Disease-- Learn to Love YourLearn to Love Your HeartHeart Michael McKee, M.D.Michael McKee, M.D. March 19, 2010March 19, 2010 #12;GoalsGoals Â·Â· Learn more about heart disease for yourself andLearn more about heart disease for yourself and for your studentsfor your students Â·Â· Learn
?Linear Gas Jet with Tailored Density Profile"
KRISHNAN, Mahadevan
2012-12-10T23:59:59.000Z
Supersonic, highly collimated gas jets and gas-filled capillary discharge waveguides are two primary targets of choice for Laser Plasma Accelerators (LPA) . Present gas jets have lengths of only 2-4 mm at densities of 1-4E19 cm-3, sufficient for self trapping and electron acceleration to energies up to ~150 MeV. Capillary structures 3 cm long have been used to accelerate beams up to 1 GeV. Capillary discharges used in LPAs serve to guide the pump laser and optimize the energy gain. A wall-stabilized capillary discharge provides a transverse profile across the channel that helps guide the laser and combat diffraction. Gas injection via a fast nozzle at one end provides some longitudinal density control, to improve the coupling. Gas jets with uniform or controlled density profiles may be used to control electron bunch injection and are being integrated into capillary experiments to add tuning of density. The gas jet for electron injection has not yet been optimized. Our Ph-I results have provided the LPA community with an alternative path to realizing a 2-3GeV electron bunch using just a gas jet. For example, our slit/blade combination gives a 15-20mm long acceleration path with tunable density profile, serving as an alternative to a 20-mm long capillary discharge with gas injection at one end. In Ph-II, we will extend these results to longer nozzles, to see whether we can synthesize 30 or 40-mm long plasma channels for LPAs.
Interfacial Ionic Liquids: Connecting Static and Dynamic Structures
Ahmet Uysal; Hua Zhou; Guang Feng; Sang Soo Lee; Song Li; Peter T. Cummings; Pasquale F. Fulvio; Sheng Dai; John K. McDonough; Yury Gogotsi; Paul Fenter
2014-12-06T23:59:59.000Z
It is well-known that room temperature ionic liquids (RTILs) often adopt a charge-separated layered structure, i.e., with alternating cation- and anion-rich layers, at electrified interfaces. However, the dynamic response of the layered structure to temporal variations in applied potential is not well understood. We used in situ, real-time X-ray reflectivity (XR) to study the potential-dependent electric double layer (EDL) structure of an imidazolium-based RTIL on charged epitaxial graphene during potential cycling as a function of temperature. The results suggest that the graphene-RTIL interfacial structure is bistable in which the EDL structure at any intermediate potential can be described by the combination of two extreme-potential structures whose proportions vary depending on the polarity and magnitude of the applied potential. This picture is supported by the EDL structures obtained by fully atomistic molecular dynamics (MD) simulations at various static potentials. The potential-driven transition between the two structures is characterized by an increasing width but with an approximately fixed hysteresis magnitude as a function of temperature. The results are consistent with the coexistence of distinct anion and cation adsorbed structures separated by an energy barrier (~0.15 eV).
Spatially resolved dynamic structure factor of finite systems from molecular dynamics simulations
Raitza, Thomas; Roepke, Gerd; Reinholz, Heidi; Morozov, Igor [Institut fuer Physik, Universitaet Rostock, D-18051 Rostock (Germany); Institut fuer Theoretische Physik, Johannes-Kepler-Universitaet Linz, A-4040 Linz, Austria and Institute of Physics, University of Western Australia, Perth, WA 6009 (Australia); Joint Institute for High Temperatures of RAS, 13 Izhorskaya Street, Building 2, Moscow RU-125412 (Russian Federation)
2011-09-15T23:59:59.000Z
The dynamical response of metallic clusters up to 10{sup 3} atoms is investigated using the restricted molecular dynamics simulations scheme. Exemplarily, a sodium like material is considered. Correlation functions are evaluated to investigate the spatial structure of collective electron excitations and the optical response of laser-excited clusters. In particular, the spectrum of bilocal correlation functions shows resonances representing different modes of collective excitations inside the nano plasma. The spatial structure, the resonance energy, and the width of the eigenmodes have been investigated for various values of electron density, temperature, cluster size, and ionization degree. Comparison with bulk properties is performed and the dispersion relation of collective excitations is discussed.
The problem of the universal density functional and the density matrix functional theory
Bobrov, V. B., E-mail: vic5907@mail.ru; Trigger, S. A., E-mail: satron@mail.ru [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)
2013-04-15T23:59:59.000Z
The analysis in this paper shows that the Hohenberg-Kohn theorem is the constellation of two statements: (i) the mathematically rigorous Hohenberg-Kohn lemma, which demonstrates that the same ground-state density cannot correspond to two different potentials of an external field, and (ii) the hypothesis of the existence of the universal density functional. Based on the obtained explicit expression for the nonrel-ativistic particle energy in a local external field, we prove that the energy of the system of more than two non-interacting electrons cannot be a functional of the inhomogeneous density. This result is generalized to the system of interacting electrons. It means that the Hohenberg-Kohn lemma cannot provide justification of the universal density functional for fermions. At the same time, statements of the density functional theory remain valid when considering any number of noninteracting ground-state bosons due to the Bose condensation effect. In the framework of the density matrix functional theory, the hypothesis of the existence of the universal density matrix functional corresponds to the cases of noninteracting particles and to interaction in the Hartree-Fock approximation.
Kerisit, Sebastien N.; Liu, Chongxuan
2014-03-03T23:59:59.000Z
Adsorption at mineral surfaces is a critical factor controlling the mobility of uranium(VI) in aqueous environments. Therefore, molecular dynamics (MD) simulations were performed to investigate uranyl(VI) adsorption onto two neutral alumino-silicate surfaces, namely the orthoclase (001) surface and the octahedral aluminum sheet of the kaolinite (001) surface. Although uranyl preferentially adsorbed as a bi-dentate innersphere complex on both surfaces, the free energy of adsorption at the orthoclase surface (-15 kcal mol-1) was significantly more favorable than that at the kaolinite surface (-3 kcal mol-1), which was attributed to differences in surface functional groups and to the ability of the orthoclase surface to dissolve a surface potassium ion upon uranyl adsorption. The structures of the adsorbed complexes compared favorably with X-ray absorption spectroscopy results. Simulations of the adsorption of uranyl complexes with up to three carbonate ligands revealed that uranyl complexes coordinated to up to 2 carbonate ions are stable on the orthoclase surface whereas uranyl carbonate surface complexes are unfavored at the kaolinite surface. Combining the MD-derived equilibrium adsorption constants for orthoclase with aqueous equilibrium constants for uranyl carbonate species indicates the presence of adsorbed uranium complexes with one or two carbonates in alkaline conditions, in support of current uranium(VI) surface complexation models.
Dynamic Adaptation of Joint Transmission Power and Contention Window in VANET
Weigle, Michele
of transmission power is crucial. We propose to decrease the transmission power for high vehicle density or high penetration ratio and increase the transmission power for lower vehicle density or penetration ratioDynamic Adaptation of Joint Transmission Power and Contention Window in VANET 1 Danda B. Rawat, 2
Southern California, University of
, and G. Z. Voyiadjis, Phys. Rev. Lett. 87, 086104 (2001). Â· Linear-scaling Density-functional-theory). Â· Hybrid Finite-element/Molecular-dynamics/Electronic-density-functional Approach to Materials Simulations). SELECTED BOOKS: Â· High Performance Computing and its Applications in the Physical Sciences, (1993), World
The impact of demographic dynamics on economic development, poverty and inequality in Mozambique
Krivobokova, Tatyana
hand and the potential to reap the benefits of a demographic gift and higher population density to reduce Africa's high fertility levels (beyond current initiatives). In a paper on population dynamics to be much smaller and partly off-set by benefits of rising population density and urbanization along
Modeling and Dynamic Management of 3D Multicore Systems with Liquid Cooling
Simunic, Tajana
in the future to address the increasing power density. Considering the high power densities in 3D systems Mi- crosystems, UC MICRO, Center for Networked Systems (CNS) at UCSD, MARCO/DARPA GSRC and NSFModeling and Dynamic Management of 3D Multicore Systems with Liquid Cooling Ayse K. Coskun , Jos
Foroutan, G. R.; Robinson, P. A.; Sobhanian, S.; Moslehi-Fard, M.; Li, B.; Cairns, I. H. [School of Physics, University of Sydney, NSW 2006, Sydney (Australia); Research Institute for Astronomy and Astrophysics of Maragha, P.O. Box 55134-441 Maragha (Iran, Islamic Republic of) and Physics Department, Faculty of Science, Sahand University of Technology, 51335-1996 Tabriz (Iran); School of Physics, University of Sydney, NSW 2006, Sydney (Australia); Research Institute for Astronomy and Astrophysics of Maragha, P.O. Box 55134-441 Maragha (Iran, Islamic Republic of) and Faculty of Physics, Tabriz University, Tabriz 51664 (Iran); Faculty of Physics, Tabriz University, Tabriz 51664 (Iran, Islamic Republic of); School of Physics, University of Sydney, NSW 2006, Sydney (Australia)
2007-01-15T23:59:59.000Z
Gas-dynamic theory is generalized to incorporate the effects of beam-driven Langmuir waves scattering off ambient density fluctuations, and the consequent effects on the propagation of a cloud of hot electrons in an inhomogeneous plasma. Assuming Langmuir scattering as the limit of nonlinear three-wave interactions with fluctuations that are weak, low-frequency, long-wavelength ion-sound waves, the net effect of scattering is equivalent to effective damping of the Langmuir waves. Under the assumption of self-similarity in the evolution of the beam and Langmuir wave distribution functions, gas-dynamic theory shows that the effects of Langmuir scattering on the beam distribution are equivalent to a perturbation in the injection profile of the beam. Analytical expressions are obtained for the height of the plateau of the beam distribution function, wave spectral number density, total wave and particle energy density, and the beam number density. The main results of gas-dynamic theory are then compared with simulation results from numerical solutions of quasilinear equations. The relaxation of the beam in velocity space is retarded in the presence of density fluctuations and the magnitude of the upper velocity boundary is less than that in the absence of fluctuations. There are four different regimes for the height of the plateau, corresponding to different stages of relaxation of the beam in velocity space. Moreover, Langmuir scattering results in transfer of electrons from moderate velocity to low velocity; this effect produces an enhancement in the beam number density at small distances near the injection site and a corresponding decrease at large distances. There are sharp decreases in the profiles of the beam and total wave energy densities, which are related to dissipation of energy at large phase velocities. Due to a slower velocity space diffusion of the beam distribution in the presence of scattering effects, the spatial width of the beam is reduced while its mean velocity of propagation increases slightly.
Dynamical Friction on extended perturbers
O. Esquivel; B. Fuchs
2008-04-01T23:59:59.000Z
Following a wave-mechanical treatment we calculate the drag force exerted by an infinite homogeneous background of stars on a perturber as this makes its way through the system. We recover Chandrasekhar's classical dynamical friction (DF) law with a modified Coulomb logarithm. We take into account a range of models that encompasses all plausible density distributions for satellite galaxies by considering the DF exerted on a Plummer sphere and a perturber having a Hernquist profile. It is shown that the shape of the perturber affects only the exact form of the Coulomb logarithm. The latter converges on small scales, because encounters of the test and field stars with impact parameters less than the size of the massive perturber become inefficient. We confirm this way earlier results based on the impulse approximation of small angle scatterings.
Relaxation dynamics in a binary hard-ellipse liquid
Wen-Sheng Xu; Zhao-Yan Sun; Li-Jia An
2014-12-01T23:59:59.000Z
Structural relaxation in binary hard spherical particles has been shown recently to exhibit a wealth of remarkable features when size disparity or mixture's composition is varied. In this paper, we test whether or not similar dynamical phenomena occur in glassy systems composed of binary hard ellipses. We demonstrate via event-driven molecular dynamics simulation that a binary hard-ellipse mixture with an aspect ratio of two and moderate size disparity displays characteristic glassy dynamics upon increasing density in both the translational and the rotational degrees of freedom. The rotational glass transition density is found to be close to the translational one for the binary mixtures investigated. More importantly, we assess the influence of size disparity and mixture's composition on the relaxation dynamics. We find that an increase of size disparity leads, both translationally and rotationally, to a speed up of the long-time dynamics in the supercooled regime so that both the translational and the rotational glass transition shift to higher densities. By increasing the number concentration of the small particles, the time evolution of both translational and rotational relaxation dynamics at high densities displays two qualitatively different scenarios, i.e., both the initial and the final part of the structural relaxation slow down for small size disparity, while the short-time dynamics still slows down but the final decay speeds up in the binary mixture with large size disparity. These findings are reminiscent of those observed in binary hard spherical particles. Therefore, our results suggest a universal mechanism for the influence of size disparity and mixture's composition on the structural relaxation in both isotropic and anisotropic particle systems.
Tariffs with Dynamic Supply Response
Karp, Larry
1985-01-01T23:59:59.000Z
Giannini FDN iibrary TARIFFS WITH DYNAMIC SUPPLY RESWNSEpaper studies the optimal tariff in a dynamic framework. Thesellers, the optimal tariff is dynam- ically inconsistent;
Oblique interactions of dust density waves
Wang, Zhelchui [Los Alamos National Laboratory; Li, Yang - Fang [MAX-PLANCK INSTITUTE; Hou, Lujing [MAX-PLANCK INSTITUTE; Jiang, Ke [MAX-PLANCK INSTITUTE; Wu, De - Jin [CHINA; Thomas, Hubertus M [MAX-PLANCK INSTITUTE; Morfill, Gregor E [MAX-PLANCK INSTITUTE
2010-01-01T23:59:59.000Z
Self-excited dust density waves (DDWs) are studied in a striped electrode device. In addition to the usual perpendicularly (with respect to the electrode) propagating DDWs, which have been frequently observed in dusty plasma experiments on the ground, a low-frequency oblique mode is also observed. This low-frequency oblique DDW has a frequency much lower than the dust plasma frequency and its spontaneous excitation is observed even with a very low dust density. It is found that the low-frequency oblique mode can exist either separately or together with the usual perpendicular mode. In the latter case, a new mode arises as a result of the interactions between the perpendicular and the oblique modes. The experiments show that these three modes satisfy the wave coupling conditions in both the frequencies and the wave-vectors.
Global coherence of dust density waves
Killer, Carsten; Melzer, André [Institut für Physik, Ernst-Moritz-Arndt-Universität Greifswald, 17489 Greifswald (Germany)
2014-06-15T23:59:59.000Z
The coherence of self-excited three-dimensional dust density waves has been experimentally investigated by comparing global and local wave properties. For that purpose, three-dimensional dust clouds have been confined in a radio frequency plasma with thermophoretic levitation. Global wave properties have been measured from the line-of-sight integrated dust density obtained from homogenous light extinction measurements. Local wave properties have been obtained from thin, two-dimensional illuminated laser slices of the cloud. By correlating the simultaneous global and local wave properties, the spatial coherence of the waves has been determined. We find that linear waves with small amplitudes tend to be fragmented, featuring an incoherent wave field. Strongly non-linear waves with large amplitudes, however, feature a strong spatial coherence throughout the dust cloud, indicating a high level of synchronization.
Development of Silica Aerogel with Any Density
M. Tabata; I. Adachi; T. Fukushima; H. Kawai; H. Kishimoto; A. Kuratani; H. Nakayama; S. Nishida; T. Noguchi; K. Okudaira; Y. Tajima; H. Yano; H. Yokogawa; H. Yoshida
Abstract–New production methods of silica aerogel with high and low refractive indices have been developed. A very slow shrinkage of alcogel at room temperature has made possible producing aerogel with high refractive indices of up to 1.265 without cracks. Even higher refractive indices than 1.08, the transmission length of the aerogel obtained from this technique has been measured to be about 10 to 20 mm at 400 nm wave length. A mold made of alcogel which endures shrinkage in the supercritical drying process has provided aerogel with the extremely low density of 0.009g/cm 3, which corresponds to the refractive index of 1.002. We have succeeded producing aerogel with a wide range of densities. I.
DENSITY FUNCTIONAL THEORY OF NORMAL AND SUPERCONDUCTING ELECTRON LIQUIDS: EXPLICIT
Gross, E.K.U.
DENSITY FUNCTIONAL THEORY OF NORMAL AND SUPERCONDUCTING ELECTRON LIQUIDS: EXPLICIT FUNCTIONALS VIAÃ?th University Nathan, Queensland 4111, Australia Abstract The basic idea of density functional theory is to map potential which is a functional of the density. The central task of density functional theory is to #12;nd
Energy-momentum Density of Gravitational Waves
Amir M. Abbassi; Saeed Mirshekari
2014-11-29T23:59:59.000Z
In this paper, we elaborate the problem of energy-momentum in general relativity by energy-momentum prescriptions theory. Our aim is to calculate energy and momentum densities for the general form of gravitational waves. In this connection, we have extended the previous works by using the prescriptions of Bergmann and Tolman. It is shown that they are finite and reasonable. In addition, using Tolman prescription, exactly, leads to same results that have been obtained by Einstein and Papapetrou prescriptions.
Fast Valuation and Calibration of Credit Default Swaps Under Levy Dynamics
Oosterlee, Cornelis W. "Kees"
Fast Valuation and Calibration of Credit Default Swaps Under L´evy Dynamics Fang Fang , Henrik J. The method presented is based on the Fourier-cosine series expansion of the underlying model's density. Having a method to generate dynamic CDS spreads available, it is also possible to value so called
Overlap population density as an index of bond strength
Gallagher, Michael James
2012-06-07T23:59:59.000Z
be eliminated. This is done by carrying out an orthogonal transformdtion on b, witn a known matrix U, viz. D = UAU' (10) Next~ M is constructed vis, the equation: M=V'D 'U (11) M transforms b to the unit matrix X: (12) Since: I ~1 MdM = U 'D PhU 'D U... on molecules of the same chemical i'amily as those under study, viz, R2-NN02, D. Thermal Decomposition of Nitramides Although estimates of the energies of bonds other than N-N, B?G. Gowcnlock, P. Jones and J. R. Majer~ Trans. Faraday Soc. ~7 23 (1981) RE...
Kwon, Suehyun
2012-01-01T23:59:59.000Z
This thesis examines three models of dynamic contracting. The first model is a model of dynamic moral hazard with partially persistent states, and the second model considers relational contracts when the states are partially ...
Dynamics of structural priming
Malhotra, Gaurav
2009-01-01T23:59:59.000Z
for understanding various aspects of syntactic priming. Cognitive processes are modelled as dynamical systems that can change their behaviour when they process information. We use these dynamical systems to investigate how each episode of language comprehension...
None
2010-04-01T23:59:59.000Z
Broad Funding Opportunity Announcement Project: FastCAP is improving the performance of an ultracapacitor—a battery-like electronic device that can complement, and possibly even replace, an HEV or EV battery pack. Ultracapacitors have many advantages over conventional batteries, including long lifespans (over 1 million cycles, as compared to 10,000 for conventional batteries) and better durability. Ultracapacitors also charge more quickly than conventional batteries, and they release energy more quickly. However, ultracapacitors have fallen short of batteries in one key metric: energy density—high energy density means more energy storage. FastCAP is redesigning the ultracapacitor’s internal structure to increase its energy density. Ultracapacitors traditionally use electrodes made of irregularly shaped, porous carbon. FastCAP’s ultracapacitors are made of tiny, aligned carbon nanotubes. The nanotubes provide a regular path for ions moving in and out of the ultracapacitor’s electrode, increasing the overall efficiency and energy density of the device.
Categorical Introduction to Dynamical Systems Symbolic Dynamical Systems
Kahng, Byung-Jay
Categorical Introduction to Dynamical Systems Symbolic Dynamical Systems Symbolic Embedding Examples Results Embeddings in Symbolic Dynamical Systems Jonathan Jaquette Swarthmore College July 22, 2009 Jonathan Jaquette Embeddings in Symbolic Dynamical Systems #12;Categorical Introduction
Eric Bergshoeff; Joaquim Gomis; Giorgio Longhi
2014-05-31T23:59:59.000Z
We investigate particles whose dynamics is invariant under the Carroll group. Although a single free such Carroll particle has no non-trivial dynamics (`the Carroll particle does not move') we show that there exists non-trivial dynamics for a set of interacting Carroll particles. Furthermore, we gauge the Carroll algebra and couple the Carroll particle to these gauge fields. It turns out that for such a coupled system even a single Carroll particle can have non-trivial dynamics.
Dynamic Simulation of DFIG Wind Turbines on FPGA Boards
Zambreno, Joseph A.
Dynamic Simulation of DFIG Wind Turbines on FPGA Boards Hao Chen, Student Member, IEEE, Song Sun is a friction coefficient. The wind turbine model is based on the relation between the upstream wind speed V w + 1 where p is the air density; Rw is the wind turbine radius; cp (A, (3) is the performance
Intramolecular and nonlinear dynamics
Davis, M.J. [Argonne National Laboratory, IL (United States)
1993-12-01T23:59:59.000Z
Research in this program focuses on three interconnected areas. The first involves the study of intramolecular dynamics, particularly of highly excited systems. The second area involves the use of nonlinear dynamics as a tool for the study of molecular dynamics and complex kinetics. The third area is the study of the classical/quantum correspondence for highly excited systems, particularly systems exhibiting classical chaos.
Dynamics of Anisotropic Universes
Jerome Perez
2006-03-30T23:59:59.000Z
We present a general study of the dynamical properties of Anisotropic Bianchi Universes in the context of Einstein General Relativity. Integrability results using Kovalevskaya exponents are reported and connected to general knowledge about Bianchi dynamics. Finally, dynamics toward singularity in Bianchi type VIII and IX universes are showed to be equivalent in some precise sence.
Atmospheric Dynamics II Instructor
AT602 Atmospheric Dynamics II 2 credits Instructor: David W. J. Thompson davet: An Introduction to Dynamic Meteorology, 5th Edition, Academic Press (recommended) Â· Marshall, J., and Plumb, R. A., 2008: Atmosphere, Ocean, and Climate Dynamics: An Introductory Text, Academic Press. Â· Vallis, G. K
Design for a Longitudinal Density Monitor for the LHC
Bart Pedersen, S; Boccardi, A; Fisher, AS; Jeff, A; Lefevre, T; Rabiller, A; Roncarolo, F; Welsch, CP
2010-01-01T23:59:59.000Z
Synchrotron radiation is currently used on the LHC for beam imaging and for monitoring the proton population in the 3 microsecond abort gap. In addition to these existing detectors, a study has been initiated to provide longitudinal density profiles of the LHC beams with a high dynamic range and a 50ps time resolution. This would allow for the precise measurement both of the bunch shape and the number of particles in the bunch tail or drifting into ghost bunches. A solution is proposed based on counting synchrotron light photons with two fast avalanche photo-diodes (APD) operated in Geiger mode. One is free-running but heavily attenuated and can be used to measure the core of the bunch. The other is much more sensitive, for measurement of the bunch tails, but must be gated off during the passage of the bunch to prevent the detector from being swamped. An algorithm is then applied to combine the two measurements and correct for the detector dead-time, after pulsing and pileup effects. Initial results from labo...
First measurements results of the LHC longitudinal density monitor
Jeff , A; Bravin, E; Boccardi, A; Bozyigit, S; Lefevre, T; Rabiller, A; Roncarolo, F; Welsch, C P; Fisher, A S
2011-01-01T23:59:59.000Z
Knowledge of the longitudinal distribution of particles is important for various aspects of accelerator operation, for example to check the injection quality and to characterize the development of ghost bunches before and during the physics periods. A new detector, the LHC Longitudinal Density Monitor (LDM) is a single-photon counting system measuring synchrotron light by means of an avalanche photodiode detector. The unprecedented energies reached in the LHC allow synchrotron light diagnostics to be used with both protons and heavy ions. The LDM is able to longitudinally profile the whole ring with a resolution close to the target of 50 ps. On-line correction for the effects of the detector deadtime, pile-up and afterpulsing allow a dynamic range of 105 to be achieved. The LDM operated during the 2010 lead ion run and during 2011 with protons. Measurements from both runs are presented in this contribution along with an analysis of the LDM performance and an outlook for future upgrades.
Impact of Dynamical Fermions on QCD Vacuum Structure
Peter J. Moran; Derek B. Leinweber
2008-01-14T23:59:59.000Z
We examine how dynamical fermions affect both the UV and infrared structure of the QCD vacuum. We consider large $28^3 \\times 96$ lattices from the MILC collaboration, using a gluonic definition of the topological charge density, founded on a new over-improved stout-link smearing algorithm. The algorithm reproduces established results from the overlap formalism and is designed to preserve nontrivial topological objects including instantons. At short distances we focus on the topological charge correlator, $$, where negative values at small $x$ reveal a sign-alternating layered structure to the topological-charge density of the QCD vacuum. We find that the magnitudes of the negative dip in the $$ correlator and the positive $$ contact term are both increased with the introduction of dynamical fermion degrees of freedom. This is in accord with expectations based on charge renormalization and the vanishing of the topological susceptibility in the chiral limit. At large distances we examine the extent to which instanton-like objects are found on the lattice, and how their distributions vary between quenched and dynamical gauge fields. We show that dynamical gauge fields contain more instanton-like objects with an average size greater than in the quenched vacuum. Finally, we directly visualize the topological charge density in order to investigate the effects of dynamical sea-quark degrees of freedom on topology.
Dynamics of the Galaxy's Satellites
James Binney
2000-06-28T23:59:59.000Z
The Milky Way's satellites provide unique information about the density of the Galactic halo at large radii. The inclusion of even a few rather inaccurate proper motions resolves an ambiguity in older mass estimates in favour of higher values. Many of the satellites are concentrated into streams. The dynamics of the Magellanic Stream provided an early indication that the halo reaches out to beyond 100 kpc. Tidal forces between the Clouds are currently disturbing the Clouds' internal dynamics. One would expect this damage to worsen rapidly as the tidal field of the MW excites the eccentricity of the Clouds' mutual orbit. This process, which has yet to be completely modelled, is important for understanding the degree of self-lensing in searches for gravitational lensing events. The Sagittarius Dwarf galaxy very likely contributes significantly to the Galactic warp. The direction of the warp's line of nodes is incorrectly predicted by the simplest models of the Dwarf's orbit. More sophisticated models, in which a complex distribution of stripped dark matter is predicted, may be more successful.
A Relativistic Dynamical Collapse Model
Philip Pearle
2014-12-21T23:59:59.000Z
A model is discussed where all operators are constructed from a quantum scalar field whose energy spectrum takes on all real values. The Schr\\"odinger picture wave function depends upon space and time coordinates for each particle, as well as an inexorably increasing evolution parameter $s$ which labels a foliation of space-like hypersurfaces. The model is constructed to be manifestly Lorentz invariant in the interaction picture. Free particle states and interactions are discussed in this framework. Then, the formalism of the CSL (Continuous Spontaneous Localization) theory of dynamical collapse is applied. The collapse-generating operator is chosen to to be the particle number space-time density. Unlike previous relativistically invariant models, the vacuum state is not excited. The collapse dynamics depends upon two parameters, a parameter $\\Lambda$ which represents the collapse rate/volume and a scale factor $\\ell$. A common example of collapse dynamics, involving a clump of matter in a superposition of two locations, is analyzed. The collapse rate is shown to be identical to that of non-relativistic CSL when the GRW-CSL choice of $\\ell=a=10^{-5}$cm, is made, along with $\\Lambda=\\lambda/a^{3}$ (GRW-CSL choice $\\lambda=10^{-16}s^{-1}$). However, it is also shown that the change of mass of a nucleon over the age of the universe is then unacceptably large. The case where $\\ell$ is the size of the universe is then considered. It is shown that the collapse behavior is satisfactory and the change of mass over the age of the universe is acceptably small, when $\\Lambda= \\lambda/\\ell a^{2}$.
Method of high-density foil fabrication
Blue, Craig A.; Sikka, Vinod K.; Ohriner, Evan K.
2003-12-16T23:59:59.000Z
A method for preparing flat foils having a high density includes the steps of mixing a powdered material with a binder to form a green sheet. The green sheet is exposed to a high intensity radiative source adapted to emit radiation of wavelengths corresponding to an absorption spectrum of the powdered material. The surface of the green sheet is heated while a lower sub-surface temperature is maintained. An apparatus for preparing a foil from a green sheet using a radiation source is also disclosed.
Nuclear Energy Density Optimization: UNEDF2
M. Kortelainen; J. McDonnell; W. Nazarewicz; E. Olsen; P. -G. Reinhard; J. Sarich; N. Schunck; S. M. Wild; D. Davesne; J. Erler; A. Pastore
2014-10-30T23:59:59.000Z
The parameters of the UNEDF2 nuclear energy density functional (EDF) model were obtained in an optimization to experimental data consisting of nuclear binding energies, proton radii, odd-even mass staggering data, fission-isomer excitation energies, and single particle energies. In addition to parameter optimization, sensitivity analysis was done to obtain parameter uncertainties and correlations. The resulting UNEDF2 is an all-around EDF. However, the sensitivity analysis also demonstrated that the limits of current Skyrme-like EDFs have been reached and that novel approaches are called for.
Low density inorganic foams fabricated using microwaves
Meek, T.T.; Blake, R.D.; Gregory, T.G.
1985-01-01T23:59:59.000Z
The objective of our work was to determine if high temperature foams could be made using microwave heating; and if so, to investigate some of their properties. Several foams were made and their compressive strengths, tensile strengths and densities were determined. Foams were made of glass, metal-glass, glass-fiber, metal-glass-fiber, and fly ash. The microwave source used was a Litton model 1521 microwave oven which operated at 2.45 GHz and had an output of 700 watts.
Symmetry energy in nuclear density functional theory
W. Nazarewicz; P. -G. Reinhard; W. Satula; D. Vretenar
2013-07-22T23:59:59.000Z
The nuclear symmetry energy represents a response to the neutron-proton asymmetry. In this survey we discuss various aspects of symmetry energy in the framework of nuclear density functional theory, considering both non-relativistic and relativistic self-consistent mean-field realizations side-by-side. Key observables pertaining to bulk nucleonic matter and finite nuclei are reviewed. Constraints on the symmetry energy and correlations between observables and symmetry-energy parameters, using statistical covariance analysis, are investigated. Perspectives for future work are outlined in the context of ongoing experimental efforts.
ARM - Lesson Plans: Air Density and Temperature
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Dynamical friction in modified Newtonian dynamics
C. Nipoti; L. Ciotti; J. Binney; P. Londrillo
2008-03-31T23:59:59.000Z
We have tested a previous analytical estimate of the dynamical friction timescale in Modified Newtonian Dynamics (MOND) with fully non-linear N-body simulations. The simulations confirm that the dynamical friction timescale is significantly shorter in MOND than in equivalent Newtonian systems, i.e. systems with the same phase-space distribution of baryons and additional dark matter. An apparent conflict between this result and the long timescales determined for bars to slow and mergers to be completed in previous N-body simulations of MOND systems is explained. The confirmation of the short dynamical-friction timescale in MOND underlines the challenge that the Fornax dwarf spheroidal poses to the viability of MOND.
Density-dependent carrier dynamics in a quantum dots-in-a-well heterostructure
Krishna, Sanjay
National Laboratories, Albuquerque, New Mexico 87185, USA 3 Department of Electrical and Computer for Integrated Nanotechnologies, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA 2 Sandia Engineering, Center for High Technology Materials, University of New Mexico, Albuquerque, New Mexico 87106
The density of states approach for the simulation of finite density quantum field theories
K. Langfeld; B. Lucini; A. Rago; R. Pellegrini; L. Bongiovanni
2015-03-02T23:59:59.000Z
Finite density quantum field theories have evaded first principle Monte-Carlo simulations due to the notorious sign-problem. The partition function of such theories appears as the Fourier transform of the generalised density-of-states, which is the probability distribution of the imaginary part of the action. With the advent of Wang-Landau type simulation techniques and recent advances, the density-of-states can be calculated over many hundreds of orders of magnitude. Current research addresses the question whether the achieved precision is high enough to reliably extract the finite density partition function, which is exponentially suppressed with the volume. In my talk, I review the state-of-play for the high precision calculations of the density-of-states as well as the recent progress for obtaining reliable results from highly oscillating integrals. I will review recent progress for the $Z_3$ quantum field theory for which results can be obtained from the simulation of the dual theory, which appears to free of a sign problem.
Material dynamics under extreme conditions of pressure and strain rate
Remington, B A; Allen, P; Bringa, E; Hawreliak, J; Ho, D; Lorenz, K T; Lorenzana, H; Meyers, M A; Pollaine, S W; Rosolankova, K; Sadik, B; Schneider, M S; Swift, D; Wark, J; Yaakobi, B
2005-09-06T23:59:59.000Z
Solid state experiments at extreme pressures (10-100 GPa) and strain rates ({approx}10{sup 6}-10{sup 8}s{sup -1}) are being developed on high-energy laser facilities, and offer the possibility for exploring new regimes of materials science. These extreme solid-state conditions can be accessed with either shock loading or with a quasi-isentropic ramped pressure drive. Velocity interferometer measurements establish the high pressure conditions. Constitutive models for solid-state strength under these conditions are tested by comparing 2D continuum simulations with experiments measuring perturbation growth due to the Rayleigh-Taylor instability in solid-state samples. Lattice compression, phase, and temperature are deduced from extended x-ray absorption fine structure (EXAFS) measurements, from which the shock-induced {alpha}-{omega} phase transition in Ti and the {alpha}-{var_epsilon} phase transition in Fe are inferred to occur on sub-nanosec time scales. Time resolved lattice response and phase can also be measured with dynamic x-ray diffraction measurements, where the elastic-plastic (1D-3D) lattice relaxation in shocked Cu is shown to occur promptly (< 1 ns). Subsequent large-scale molecular dynamics (MD) simulations elucidate the microscopic dynamics that underlie the 3D lattice relaxation. Deformation mechanisms are identified by examining the residual microstructure in recovered samples. The slip-twinning threshold in single-crystal Cu shocked along the [001] direction is shown to occur at shock strengths of {approx}20 GPa, whereas the corresponding transition for Cu shocked along the [134] direction occurs at higher shock strengths. This slip-twinning threshold also depends on the stacking fault energy (SFE), being lower for low SFE materials. Designs have been developed for achieving much higher pressures, P > 1000 GPa, in the solid state on the National Ignition Facility (NIF) laser.
Zhao, Bo; Huang, Jinfan, E-mail: jinfanh@umich.edu; Bartell, Lawrence S.
2013-11-15T23:59:59.000Z
Molecular dynamics (MD) computer simulations have been carried out and a novel modified technique of Voronoi polyhedra has been performed to identify solid-like particles in a molten nanoparticle. This technique works quite well in analyzing the effects of particle size on nucleation rates of iron nanoparticles in the temperature range of 750–1160 K. Nanoparticles with 1436 and 2133 Fe atoms have been examined and the results are compared with those obtained earlier with Fe{sub 331} nanoparticles. Nucleation rates for freezing obtained from MD simulations for Fe{sub 2133} vary from 8.8×10{sup 34} m{sup 3}/s to 4.1×10{sup 35} m{sup 3}/s at over a temperature range from 1160 K to 900 K, Rates for. Fe{sub 1436} and Fe{sub 331} are somewhat higher. Nucleation rates increase as supercooling deepens until the viscosity of the liquid increases sharply enough to slow down the rate. Bt applying classical nucleation theory, the interfacial free energy between solid and liquid cab be estimated From this and other thermodynamic information can be derived a theoretical expression for the size-dependence of the heat of fusion of nanoparticles. Results agreed quite well with those observed in our MD observations. An earlier expression in the literature for this size-dependence was shown to be incorrect. The size dependence of melting point is discussed. - Graphical abstract: Critical nuclei of crystallization. Display Omitted - Highlights: • Solid state material synthesis. • Material structure. • Experimental study of nucleation in condensed materials. • Computation study of nucleation in condensed materials.
Nguyen, Ba Nghiep; Gao, Fei; Henager, Charles H.; Kurtz, Richard J.
2014-05-01T23:59:59.000Z
This article proposes a new method to estimate the thermal conductivity of SiC/SiC composites subjected to neutron irradiation. The modeling method bridges different scales from the atomic scale to the scale of a 2D SiC/SiC composite. First, it studies the irradiation-induced point defects in perfect crystalline SiC using molecular dynamics (MD) simulations to compute the defect thermal resistance as a function of vacancy concentration and irradiation dose. The concept of defect thermal resistance is explored explicitly in the MD data using vacancy concentrations and thermal conductivity decrements due to phonon scattering. Point defect-induced swelling for chemical vapor deposited (CVD) SiC as a function of irradiation dose is approximated by scaling the corresponding MD results for perfect crystal ?-SiC to experimental data for CVD-SiC at various temperatures. The computed thermal defect resistance, thermal conductivity as a function of grain size, and definition of defect thermal resistance are used to compute the thermal conductivities of CVD-SiC, isothermal chemical vapor infiltrated (ICVI) SiC and nearly-stoichiometric SiC fibers. The computed fiber and ICVI-SiC matrix thermal conductivities are then used as input for an Eshelby-Mori-Tanaka approach to compute the thermal conductivities of 2D SiC/SiC composites subjected to neutron irradiation within the same irradiation doses. Predicted thermal conductivities for an irradiated Tyranno-SA/ICVI-SiC composite are found to be comparable to available experimental data for a similar composite ICVI-processed with these fibers.
Non-power law behavior of the radial profile of phase-space density of halos
Popolo, A. Del, E-mail: adelpopolo@oact.inaf.it [Dipartimento di Fisica e Astronomia, University Of Catania, Viale Andrea Doria 6, 95125 Catania (Italy)
2011-07-01T23:59:59.000Z
We study the pseudo phase-space density, ?(r)/?{sup 3}(r), of ?CDM dark matter halos with and without baryons (baryons+DM, and pure DM), by using the model introduced in Del Popolo (2009), which takes into account the effect of dynamical friction, ordered and random angular momentum, baryons adiabatic contraction and dark matter baryons interplay. We examine the radial dependence of ?(r)/?{sup 3}(r) over 9 orders of magnitude in radius for structures on galactic and cluster of galaxies scales. We find that ?(r)/?{sup 3}(r) is approximately a power-law only in the range of halo radius resolved by current simulations (down to 0.1% of the virial radius) while it has a non-power law behavior below the quoted scale, with inner profiles changing with mass. The non-power-law behavior is more evident for halos constituted both of dark matter and baryons while halos constituted just of dark matter and with angular momentum chosen to reproduce a Navarro-Frenk-White (NFW) density profile, are characterized by an approximately power-law behavior. The results of the present paper lead to conclude that density profiles of the NFW type are compatible with a power-law behavior of ?(r)/?{sup 3}(r), while those flattening to the halo center, like those found in Del Popolo (2009) or the Einasto profile, or the Burkert profile, cannot produce radial profile of the pseudo-phase-space density that are power-laws at all radii. The results argue against universality of the pseudo phase-space density and as a consequence argue against universality of density profiles constituted by dark matter and baryons as also discussed in Del Popolo (2009)
Stephen, Alton Lee
1968-01-01T23:59:59.000Z
Average molecular velocity Cartesian length co-ordinate Thermal accomodation co-efficient Constant used in Appendix I Element of volume in velocity space Angular displacement Viscosity co-efficient Gas density cm cm/sec cm/sec cm/sec cm... on spheres in a rarefied gas as a means of making correc- tions to the results of Millikan's oil drop experiment. 4 Sanger's work was followed by a paper in which Tsien out- lined the field of low density, high speed gas dynamics. In this work, Tsien used...
High Energy Density Science at the Linac Coherent Light Source
Lee, R W
2007-10-19T23:59:59.000Z
High energy density science (HEDS), as a discipline that has developed in the United States from National Nuclear Security Agency (NNSA)-sponsored laboratory research programs, is, and will remain, a major component of the NNSA science and technology strategy. Its scientific borders are not restricted to NNSA. 'Frontiers in High Energy Density Physics: The X-Games of Contemporary Science' identified numerous exciting scientific opportunities in this field, while pointing to the need for a overarching interagency plan for its evolution. Meanwhile, construction of the first x-ray free-electron laser, the Office-of-Science-funded Linear Coherent Light Source-LCLS: the world's first free electron x-ray laser, with 100-fsec time resolution, tunable x-ray energies, a high rep rate, and a 10 order-of-magnitude increase in brightness over any other x-ray source--led to the realization that the scientific needs of NNSA and the broader scientific community could be well served by an LCLS HEDS endstation employing both short-pulse and high-energy optical lasers. Development of this concept has been well received in the community. NNSA requested a workshop on the applicability of LCLS to its needs. 'High Energy Density Science at the LCLS: NNSA Defense Programs Mission Need' was held in December 2006. The workshop provided strong support for the relevance of the endstation to NNSA strategic requirements. The range of science that was addressed covered a wide swath of the vast HEDS phase space. The unique possibilities provided by the LCLS in areas of intense interest to NNSA Defense Programs were discussed. The areas of focus included warm dense matter and equations of state, hot dense matter, and behavior of high-pressure materials under conditions of high strain-rate and extreme dynamic loading. Development of new and advanced diagnostic techniques was also addressed. This report lays out the relevant science, as brief summaries (Ch. II), expanded descriptions (Ch. V), and a more detailed plans for experiments (Ch. VI), highlighting the uniqueness the HEDS endstation will play in providing mission-relevant HED data and in the development of the field. One of the more exciting aspects of NNSA-relevant experiments on LCLS is that, given the extraordinary investment and consequent advances in accurate atomic-scale simulations of matter (to a large extent via the Accelerated Scientific Computing program sponsored by NNSA), the facility will provide a platform that, for the first time, will permit experiments in the regimes of interest at the time and spatial scales of the simulations. In Chapter III, the report places the potential of LCLS with an HED science endstation in the context of science required by NNSA, as well as explicating the relationship of NNSA and HED science in general. Chapter IV discusses 4th-generation light sources, like LCLS, in the context of other laboratory technologies presently utilized by NNSA. The report concludes, noting that an HED endstation on LCLS can provide access to data in regimes that are relevant to NNSA needs but no mechanism exists for providing such data. The endstation will also serve to build a broad-based community in the 'X-Games' of physics. The science generated by the facility will be a collaboration of NNSA-based laboratory scientists and university-based researchers. The LCLS endstation fulfills the need for an intermediate-scale facility capable of delivering fundamental advances and mission-relevant research in high energy density science.
Dynamical insight into dark-matter haloes
Walter Dehnen; Dean McLaughlin
2005-06-22T23:59:59.000Z
We investigate, using the spherical Jeans equation, self-gravitating dynamical equilibria satisfying a relation rho/sigma_r^3 propto r^-alpha, which holds for simulated dark-matter haloes over their whole resolved radial range. Considering first the case of velocity isotropy, we find that this problem has only one solution with realistic density profile, which occurs only for a critical value of alpha_crit = 35/18 ~= 1.94, which is consistent with the empirical value of 1.9+/-0.05. We extend our analysis in two ways: first we introduce a parameter epsilon to allow for a more general relation rho/\\sigma_r^epsilon propto r^-alpha; second we consider velocity anisotropy. If we assume beta(r) := 1- sigma_theta^2 / sigma_r^2 to be linearly related to the logarithmic density slope gamma(r) := -dln(rho)/dln(r), which is in agreement with simulations, the problem remains analytically tractable and is equivalent to the simpler isotropic case: there exists only one physical solution, which occurs at a critical alpha value. Remarkably, this value of alpha and the density and velocity-dispersion profiles depend only on epsilon and the value beta_0 := beta(r=0), but not on the slope of the linear beta-gamma relation. For epsilon=3, alpha_crit = 35/18 - 2beta_0/9 and the resulting density profile is fully analytic (as are the velocity dispersion and circular speed) with an inner cusp rho propto r^{-(7+10beta_0)/9} and a very smooth transition to a steeper outer power-law asymptote. These models are in excellent agreement with the density, velocity-dispersion and anisotropy profiles of simulated dark-matter haloes over their full resolved radial range. If epsilon=3 is a universal constant, some scatter in beta_0 ~= 0 may account for some diversity in the density profiles. (ABRIDGED)
Structure formation: a spherical model for the evolution of the density distribution
P. Valageas
1998-07-02T23:59:59.000Z
Within the framework of hierarchical clustering we show that a simple Press-Schechter-like approximation, based on spherical dynamics, provides a good estimate of the evolution of the density field in the quasi-linear regime up to $\\Sigma \\sim 1$. Moreover, it allows one to recover the exact series of the cumulants of the probability distribution of the density contrast in the limit $\\Sigma \\to 0$ which sheds some light on the rigorous result and on ``filtering''. We also obtain similar results for the divergence of the velocity field. Next, we extend this prescription to the highly non-linear regime, using a stable-clustering approximation. Then we recover a specific scaling of the counts-in-cells which is indeed seen in numerical simulations, over a well-defined range. To this order we also introduce an explicit treatment of the behaviour of underdensities, which takes care of the normalization and is linked to the low-density bubbles and the walls one can see in numerical simulations. We compare this to a 1-dimensional adhesion model, and we present the consequences of our prescription for the power-law tail and the cutoff of the density distribution.
Analysis of Quantum Particle Automata for Solving the Density Classification Problem
Tina Yu; Radel Ben-Av
2015-01-16T23:59:59.000Z
To advance our understanding of Quantum Cellular Automata in problem solving through parallel and distributed computing, this research quantized the density classification problem and adopted the Quantum Particle Automata (QPA) to solve the quantized problem. In order to solve this problem, the QPA needed a unitary operator to carry out the QPA evolution and a boundary partition to make the classification decisions. We designed a Genetic Algorithm (GA) to search for the unitary operators and the boundary partitions to classify the density of binary inputs with length 5. The GA was able to find more than one unitary operator that can transform the QPA in ways such that when the particle was measured, it was more likely to collapse to the basis states that were on the correct side of the boundary partition for the QPA to decide if the binary input had majority density 0 or majority density 1. We analyzed these solutions and found that the QPA evolution dynamic was driven by a particular parameter $\\theta$ of the unitary operator: a small $\\theta$ gave the particle small mass hence fast evolution while large $\\theta$ had the opposite effect. While these results are encouraging, scaling these solutions for binary inputs of arbitrary length of $n$ requires additional analysis, which we will investigate in our future work.
A. S. Umar; V. E. Oberacker
2007-09-25T23:59:59.000Z
We study fusion reactions of the $^{64}$Ni+$^{64}$Ni system using the density-constrained time-dependent Hartree-Fock (TDHF) formalism. In this formalism the fusion barriers are directly obtained from TDHF dynamics. In addition, we incorporate the entrance channel alignments of the slightly deformed (oblate) $^{64}$Ni nuclei due to dynamical Coulomb excitation. We show that alignment leads to a fusion barrier distribution and alters the naive picture for defining which energies are actually sub-barrier. We also show that core polarization effects could play a significant role in fusion cross section calculations.
Backward Clusters, Hierarchy and Wild Sums for a Hard Sphere System in a Low-Density Regime
K. Aoki; M. Pulvirenti; S. Simonella; T. Tsuji
2014-08-27T23:59:59.000Z
We study the statistics of backward clusters in a gas of hard spheres at low density. A backward cluster is defined as the group of particles involved directly or indirectly in the backwards-in-time dynamics of a given tagged sphere. We derive upper and lower bounds on the average size of clusters by using the theory of the homogeneous Boltzmann equation combined with suitable hierarchical expansions. These representations are known in the easier context of Maxwellian molecules (Wild sums). We test our results with a numerical experiment based on molecular dynamics simulations.
High density Ru nanocrystal deposition for nonvolatile memory applications
High density Ru nanocrystal deposition for nonvolatile memory applications Damon B. Farmer School density optimizes the charge storing capability of the floating layer, while a high degree of size
Wood-Fiber/High-Density-Polyethylene Composites: Compounding Process
Wood-Fiber/High-Density-Polyethylene Composites: Compounding Process J. Z. Lu,1 Q. Wu,1 I. I parameters for the wood-fiber/high-density-polyethylene blends at 60 rpm were a temperature of 180Â°C
Experimental bond critical point and local energy density properties...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Mn-O, Fe-O and Co-O bonded interactions for Abstract: Bond critical point, bcp, and local energy density properties for the electron density, ED, distributions, calculated with...
Innovative fuel designs for high power density pressurized water reactor
Feng, Dandong, Ph. D. Massachusetts Institute of Technology
2006-01-01T23:59:59.000Z
One of the ways to lower the cost of nuclear energy is to increase the power density of the reactor core. Features of fuel design that enhance the potential for high power density are derived based on characteristics of ...
Design of annular fuel for high power density BWRs
Morra, Paolo
2005-01-01T23:59:59.000Z
Enabling high power density in the core of Boiling Water Reactors (BWRs) is economically profitable for existing or new reactors. In this work, we examine the potential for increasing the power density in BWR plants by ...
Constrained Density-Functional Theory--Configuration Interaction
Kaduk, Benjamin James
2012-01-01T23:59:59.000Z
In this thesis, I implemented a method for performing electronic structure calculations, "Constrained Density Functional Theory-- Configuration Interaction" (CDFT-CI), which builds upon the computational strengths of Density ...
Heterogeneous perturbation of fluid density and solid elastic strain in consolidating porous media
P. Artale Harris; E. N. M. Cirillo; G. Sciarra
2014-07-20T23:59:59.000Z
The occurrence of heterogeneous perturbations of fluid mass density and solid elastic strain of a porous continuum, as a consequence of its undrained response is a very important topic in theoretical and applied poromechanics. The classical Mandel--Cryer effect provides an explanation of fluid overpressure in the central region of a porous sample, immediately after the application of the loading. However this effect fades away when the fluid leaks out of the porous network. Here this problem is studied within the framework of a second gradient theory and a thorough description of the static and the dynamics of the phenomenon is given.
Tuning Range-Separated Density Functional Theory for Photocatalytic Water Splitting Systems
Bokareva, Olga S; Bokarev, Sergey I; Kühn, Oliver
2015-01-01T23:59:59.000Z
We discuss the applicability of long-range separated density functional theory (DFT) to the prediction of electronic transitions of a particular photocatalytic system based on an Ir(III) photosensitizer (IrPS). Special attention is paid to the charge-transfer properties which are of key importance for the photoexcitation dynamics, but and cannot be correctly described by means of conventional DFT. The optimization of the range-separation parameter is discussed for IrPS including its complexes with electron donors and acceptors used in photocatalysis. Particular attention is paid to the problems arising for a description of medium effects by a polarizable continuum model.
Smooth Quantum Dynamics of Mixmaster Universe
Bergeron, Hervé; Gazeau, Jean Pierre; Ma?kiewicz, Przemys?aw; Piechocki, W?odzimierz
2015-01-01T23:59:59.000Z
We present a quantum version of the vacuum Bianchi IX model by implementing affine coherent state quantization combined with a Born-Oppenheimer-like adiabatic approximation. The analytical treatment is carried out on both quantum and semiclassical levels. The resolution of the classical singularity occurs by means of a repulsive potential generated by our quantization procedure. The quantization of the oscillatory degrees of freedom produces a radiation energy density term in the semiclassical constraint equation. The Friedmann-like lowest energy eigenstates of the system are found to be dynamically stable.
DYNAMICAL MODEL OF AN EXPANDING SHELL
Pe'er, Asaf [Harvard-Smithsonian Center for Astrophysics, MS-51, 60 Garden Street, Cambridge, MA 02138 (United States)
2012-06-10T23:59:59.000Z
Expanding blast waves are ubiquitous in many astronomical sources, such as supernova remnants, X-ray emitting binaries, and gamma-ray bursts. I consider here the dynamics of such an expanding blast wave, both in the adiabatic and the radiative regimes. As the blast wave collects material from its surroundings, it decelerates. A full description of the temporal evolution of the blast wave requires consideration of both the energy density and the pressure of the shocked material. The obtained equation is different from earlier works in which only the energy was considered. The solution converges to the familiar results in both the ultrarelativistic and the sub-relativistic (Newtonian) regimes.
Nonlinear dynamics of a regenerative cutting process
Grzegorz Litak; Sven Schubert; Guenter Radons
2012-01-24T23:59:59.000Z
We examine the regenerative cutting process by using a single degree of freedom non-smooth model with a friction component and a time delay term. Instead of the standard Lyapunov exponent calculations, we propose a statistical 0-1 test analysis for chaos detection. This approach reveals the nature of the cutting process signaling regular or chaotic dynamics. For the investigated deterministic model we are able to show a transition from chaotic to regular motion with increasing cutting speed. For two values of time delay showing the different response the results have been confirmed by the means of the spectral density and the multiscaled entropy.
High energy density redox flow device
Chiang, Yet-Ming; Carter, W. Craig; Ho, Bryan Y; Duduta, Mihai; Limthongkul, Pimpa
2014-05-13T23:59:59.000Z
Redox flow devices are described in which at least one of the positive electrode or negative electrode-active materials is a semi-solid or is a condensed ion-storing electroactive material, and in which at least one of the electrode-active materials is transported to and from an assembly at which the electrochemical reaction occurs, producing electrical energy. The electronic conductivity of the semi-solid is increased by the addition of conductive particles to suspensions and/or via the surface modification of the solid in semi-solids (e.g., by coating the solid with a more electron conductive coating material to increase the power of the device). High energy density and high power redox flow devices are disclosed. The redox flow devices described herein can also include one or more inventive design features. In addition, inventive chemistries for use in redox flow devices are also described.
Ternary liquid mixture viscosities and densities
Wei, I.C.; Rowley, R.L.
1984-01-01T23:59:59.000Z
Liquid mixture viscosities and densities have been measured at 298.15 K and ambient pressure for 20 ternary systems. Twelve ternary compositions, encompassing the entire composition range, have been chosen for each system in an effort to test a newly proposed predictive equation based on local compositions. Viscosities calculated by using the local composition model agreed with the experimental data within an average absolute deviation of 6.4%. No adjustable parameters were used and only binary interactions in the form of NRTL constants were input. The results of these studies indicate that the local composition model predictions are generally as good for multicomponent systems as they are for the corresponding binaries. 24 references, 3 tables.
Energy density fluctuations in early universe
Guardo, G. L.; Ruggieri, M. [Department of Physics and Astronomy, University of Catania, Catania (Italy); Greco, V. [Department of Physics and Astronomy, University of Catania, Catania, Italy and INFN - Laboratori Nazionali del Sud, Catania (Italy)
2014-05-09T23:59:59.000Z
The primordial nucleosinthesys of the element can be influenced by the transitions of phase that take place after the Big Bang, such as the QCD transition. In order to study the effect of this phase transition, in this work we compute the time evolution of thermodynamical quantities of the early universe, focusing on temperature and energy density fluctuations, by solving the relevant equations of motion using as input the lattice QCD equation of state to describe the strongly interacting matter in the early universe plasma. We also study the effect of a primordial strong magnetic field by means of a phenomenological equation of state. Our results show that small inhomogeneities of strongly interacting matter in the early Universe are moderately damped during the crossover.
Competition between superconductivity and spin density wave
Tian De Cao
2012-08-25T23:59:59.000Z
The Hubbard model has been investigated widely by many authors, while this work may be new in two aspects. One, we focus on the possible effects of the positions of the gaps associated with the pairing and the spin density wave. Two, we suggest that the models with different parameters are appropriate for different materials (or a material in different doped regions). This will lead to some new insights into the high temperature superconductors. It is shown that the SDW can appear at some temperature region when the on-site Coulomb interaction is larger, while the SC requires a decreased U at a lower temperature. This can qualitatively explain the relationship between superconducting and pseudogap states of Cu-based superconductors in underdoped and optimally doped regions. The superinsulator is also discussed.
LATTICE QCD AT FINITE TEMPERATURE AND DENSITY.
BLUM,T.; CREUTZ,M.; PETRECZKY,P.
2004-02-24T23:59:59.000Z
With the operation of the RHIC heavy ion program, the theoretical understanding of QCD at finite temperature and density has become increasingly important. Though QCD at finite temperature has been extensively studied using lattice Monte-Carlo simulations over the past twenty years, most physical questions relevant for RHIC (and future) heavy ion experiments remain open. In lattice QCD at finite temperature and density there have been at least two major advances in recent years. First, for the first time calculations of real time quantities, like meson spectral functions have become available. Second, the lattice study of the QCD phase diagram and equation of state have been extended to finite baryon density by several groups. Both issues were extensively discussed in the course of the workshop. A real highlight was the study of the QCD phase diagram in (T, {mu})-plane by Z. Fodor and S. Katz and the determination of the critical end-point for the physical value of the pion mass. This was the first time such lattice calculations at, the physical pion mass have been performed. Results by Z Fodor and S. Katz were obtained using a multi-parameter re-weighting method. Other determinations of the critical end point were also presented, in particular using a Taylor expansion around {mu} = 0 (Bielefeld group, Ejiri et al.) and using analytic continuation from imaginary chemical potential (Ph. de Forcrand and O. Philipsen). The result based on Taylor expansion agrees within errors with the new prediction of Z. Fodor and S. Katz, while methods based on analytic continuation still predict a higher value for the critical baryon density. Most of the thermodynamics studies in full QCD (including those presented at this workshop) have been performed using quite coarse lattices, a = 0.2-0.3 fm. Therefore one may worry about cutoff effects in different thermodynamic quantities, like the transition temperature T{sub tr}. At the workshop U. Heller presented a study of the transition temperature for three different lattice spacings and performed a continuum extrapolation of T{sub tr} for the first time. Lattice calculations of the meson spectral functions were presented by M. Asakawa, S. Datta, E. Laermann and H. Matsufuru. These show that charmonia ground states ({eta}{sub c} and J/{psi}) continue to exist in the plasma at least up to a temperature of 1.7 T{sub tr}. At what temperature charmonia states cease to exist is not yet clear. Calculations presented by M. Asakawa show dissolution of the J/{psi} at T = 1.7 T{sub tr}, while the analysis presented H. Matsufuru provided evidence that ground state charmonia still exist at this temperature. S. Datta argued that the ground state charmonia is likely to dissolve only for temperatures T > 2.25 T{sub tr}, while the P-states are dissociated at, 1.1 T{sub tr}. It is also very interesting that, even in the case of light quarks, meson spectral functions show a resonance-like structure in the plasma phase (talk by E. Laermann). Finally attempts to calculate transport properties in the Quark Gluon Plasma were presented by S. Gupta. The workshop devoted special attention to the finite temperature modification of inter-quark forces and color screening, another area where considerable progress has been made in recent years (talks by 0. Kaczmarek, K. Petrov, O. Philipsen and F. Zantow). Many other new theoretical developments which cannot be discussed here were also presented on the workshop. Altogether the workshop was a great success, for which we thank all the participants.
Nanoindentation Under Dynamic Conditions
Wheeler, Jeffrey M
2009-05-22T23:59:59.000Z
............................................................................................ 98 6.3.1 Data Analysis ........................................................................................... 99 6.3.2 Dynamic Compliance ............................................................................. 103 6.3.3 Strain Rates...
Shape Dynamics. An Introduction
Julian Barbour
2011-05-01T23:59:59.000Z
Shape dynamics is a completely background-independent universal framework of dynamical theories from which all absolute elements have been eliminated. For particles, only the variables that describe the shapes of the instantaneous particle configurations are dynamical. In the case of Riemannian three-geometries, the only dynamical variables are the parts of the metric that determine angles. The local scale factor plays no role. This leads to a shape-dynamic theory of gravity in which the four-dimensional diffeomorphism invariance of general relativity is replaced by three-dimensional diffeomorphism invariance and three-dimensional conformal invariance. Despite this difference of symmetry groups, it is remarkable that the predictions of the two theories -- shape dynamics and general relativity -- agree on spacetime foliations by hypersurfaces of constant mean extrinsic curvature. However, the two theories are distinct, with shape dynamics having a much more restrictive set of solutions. There are indications that the symmetry group of shape dynamics makes it more amenable to quantization and thus to the creation of quantum gravity. This introduction presents in simple terms the arguments for shape dynamics, its implementation techniques, and a survey of existing results.
Aurel Bulgac
2012-04-10T23:59:59.000Z
I describe the foundation of a Density Functional Theory approach to include pairing correlations, which was applied to a variety of systems ranging from dilute fermions, to neutron stars and finite nuclei. Ground state properties as well as properties of excited states and time-dependent phenomena can be achieved in this manner within a formalism based on microscopic input.
Quantum coherent switch utilizing commensurate nanoelectrode and charge density periodicities
Harrison, Neil (Santa Fe, NM); Singleton, John (Los Alamos, NM); Migliori, Albert (Santa Fe, NM)
2008-08-05T23:59:59.000Z
A quantum coherent switch having a substrate formed from a density wave (DW) material capable of having a periodic electron density modulation or spin density modulation, a dielectric layer formed onto a surface of the substrate that is orthogonal to an intrinsic wave vector of the DW material; and structure for applying an external spatially periodic electrostatic potential over the dielectric layer.
ORIGINAL PAPER BambooFiber Filled High Density Polyethylene Composites
ORIGINAL PAPER BambooÂFiber Filled High Density Polyethylene Composites: Effect of Coupling Springer Science+Business Media, LLC 2008 Abstract High density polyethylene (HDPE)/bamboo composites in the future study. Keywords Bamboo Ã High density polyethylene Ã Coupling treatment Ã Nanoclay Introduction
HIGHLIGHT OF THE MONTH Orbital Functionals in Density Functional Theory
Gross, E.K.U.
HIGHLIGHT OF THE MONTH Orbital Functionals in Density Functional Theory: The Optimized E#11;ectiveurzburg, Am Hubland, D-97074 Wurzburg, Germany The success of density functional theory hinges the development of modern density functional theory. In present-day language, the exact OEP should be called
Electronic excitations in complex systems: beyond density functional theory
Botti, Silvana
Electronic excitations in complex systems: beyond density functional theory for real materials . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17 3 Time-dependent density functional theory 19 3.1 The Runge-Gross theorem . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 27 4 Model kernels from many-body perturbation theory 29 4.1 Time-dependent density functional theory
A Guided Tour of TimeDependent Density Functional Theory
Gross, E.K.U.
A Guided Tour of TimeÂDependent Density Functional Theory Kieron Burke 1 and E.K.U. Gross 2 1 outlook. 1 Introduction and User's Guide Density functional theory is the study of the one in density functional theory, driven largely by its applications in quantum chemistry[3]. This is due
EFFECTIVE MAXWELL EQUATIONS FROM TIME-DEPENDENT DENSITY FUNCTIONAL THEORY
Bigelow, Stephen
EFFECTIVE MAXWELL EQUATIONS FROM TIME-DEPENDENT DENSITY FUNCTIONAL THEORY WEINAN E, JIANFENG LU and magnetic fields are derived starting from time-dependent density functional theory. Effective permittivity with the density functional theory [2Â4] instead of the many-body SchrÂ¨odinger or Dirac equations. This is because
Density Functional Theory applied to the solid state...
Adler, Joan
Density Functional Theory applied to the solid state... An introduction to VASP Jeremie Zaffran 2nd Marom (PhD) #12;Contents I- DFT and its functionals A. On the density functional theory... B #12;I- DFT and its functionals #12;I-DFT and its functionals A- On the density functional theory Why
Benchmark density functional theory calculations for nanoscale conductance
Thygesen, Kristian
Benchmark density functional theory calculations for nanoscale conductance M. Strange,a I. S. The transmission functions are calculated using two different density functional theory methods, namely state density functional theory DFT . The resulting NEGF- DFT formalism provides a numerically efficient
1 Density Functional Theory for Emergents Robert O. Jones
1 Density Functional Theory for Emergents Robert O. Jones Peter-GrÂ¨unberg-Institut PGI-1 and German the widespread use of density functional (DF) theory in materials science and chemistry and the physical insight as basic variable 3 3 An "approximate practical method" 5 4 Density functional formalism 7 4.1 Single
THE MANY-ELECTRON ENERGY IN DENSITY FUNCTIONAL THEORY
Armiento, Rickard
THE MANY-ELECTRON ENERGY IN DENSITY FUNCTIONAL THEORY From Exchange-Correlation Functional Design to the configuration of its electrons. Computer programs based on density functional theory (DFT) can calculate applicable within the field of computational density functional theory. Sammanfattning Att fÃ¶rutsÃ¤ga
Time Dependent Density Functional Theory Applications, limitations and ... new frontiers
Botti, Silvana
Time Dependent Density Functional Theory Applications, limitations and ... new frontiers Francesco Spectroscopy Facility (ETSF) Vienna, 19 January 2007 1/55 Time Dependent Density Functional Theory Francesco Sottile #12;Time-Dependent Density Functional Theory Applications and results: The ETSF Outline 1 Time
RELATIVISTIC DENSITY FUNCTIONAL THEORY: FOUNDATIONS AND BASIC FORMALISM
Engel, Eberhard
1 Chapter 10 RELATIVISTIC DENSITY FUNCTIONAL THEORY: FOUNDATIONS AND BASIC FORMALISM E. Engela a An overview of relativistic density functional theory (RDFT) is presented with special emphasis on its field-Cluster schemes in recent years density functional theory (DFT) still represents the method of choice
Inverse diffusion from knowledge of power densities Guillaume Bal
Bal, Guillaume
asymptotic expansions and (Fourier) transformation, this allow us to construct the power density) provides access to the power density H(x) = (x)|u|2 (x) for all x inside the domain of interestInverse diffusion from knowledge of power densities Guillaume Bal , Eric Bonnetier , Fran
Density of the Values Set of the Tau Function
N. A. Carella
2014-04-10T23:59:59.000Z
It is shown that the density of the values set {Tau(n): n > x/log x. The currently known density is #{Tau(n) : n > x^(1/2+o(1)), and the expected density is #{Tau(n) : n 2, which arises as a singular case of this analysis, is discussed within.
Dynamic structural disorder in supported nanoscale catalysts
Rehr, J. J.; Vila, F. D. [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)] [Department of Physics, University of Washington, Seattle, Washington 98195 (United States)
2014-04-07T23:59:59.000Z
We investigate the origin and physical effects of “dynamic structural disorder” (DSD) in supported nano-scale catalysts. DSD refers to the intrinsic fluctuating, inhomogeneous structure of such nano-scale systems. In contrast to bulk materials, nano-scale systems exhibit substantial fluctuations in structure, charge, temperature, and other quantities, as well as large surface effects. The DSD is driven largely by the stochastic librational motion of the center of mass and fluxional bonding at the nanoparticle surface due to thermal coupling with the substrate. Our approach for calculating and understanding DSD is based on a combination of real-time density functional theory/molecular dynamics simulations, transient coupled-oscillator models, and statistical mechanics. This approach treats thermal and dynamic effects over multiple time-scales, and includes bond-stretching and -bending vibrations, and transient tethering to the substrate at longer ps time-scales. Potential effects on the catalytic properties of these clusters are briefly explored. Model calculations of molecule-cluster interactions and molecular dissociation reaction paths are presented in which the reactant molecules are adsorbed on the surface of dynamically sampled clusters. This model suggests that DSD can affect both the prefactors and distribution of energy barriers in reaction rates, and thus can significantly affect catalytic activity at the nano-scale.
E-Print Network 3.0 - atomic oxygen densities Sample Search Results
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
densities Search Powered by Explorit Topic List Advanced Search Sample search results for: atomic oxygen densities...
E-Print Network 3.0 - atomic oxygen density Sample Search Results
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
density Search Powered by Explorit Topic List Advanced Search Sample search results for: atomic oxygen density...
Conformal Higgs model: predicted dark energy density
R. K. Nesbet
2014-11-03T23:59:59.000Z
Postulated universal Weyl conformal scaling symmetry provides an alternative to the $\\Lambda$CDM paradigm for cosmology. Recent applications to galactic rotation velocities, Hubble expansion, and a model of dark galactic halos explain qualitative phenomena and fit observed data without invoking dark matter. Significant revision of theory relevant to galactic collisions and clusters is implied, but not yet tested. Dark energy is found to be a consequence of conformal symmetry for the Higgs scalar field of electroweak physics. The present paper tests this implication. The conformal Higgs model acquires a gravitational effect described by a modified Friedmann cosmic evolution equation, shown to fit cosmological data going back to the cosmic microwave background epoch. The tachyonic mass parameter of the Higgs model becomes dark energy in the Friedmann equation. A dynamical model of this parameter, analogous to the Higgs mechanism for gauge boson mass, is derived and tested here. An approximate calculation yields a result consistent with the empirical magnitude inferred from Hubble expansion.
Dynamics of polymers: A mean-field theory
Fredrickson, Glenn H. [Department of Chemical Engineering, University of California, Santa Barbara, California 93106 (United States) [Department of Chemical Engineering, University of California, Santa Barbara, California 93106 (United States); Materials Research Laboratory, University of California, Santa Barbara, California 93106 (United States); Department of Materials, University of California, Santa Barbara, California 93106 (United States); Orland, Henri [Institut de Physique Théorique, CE-Saclay, CEA, F-91191 Gif-sur-Yvette Cedex (France)] [Institut de Physique Théorique, CE-Saclay, CEA, F-91191 Gif-sur-Yvette Cedex (France)
2014-02-28T23:59:59.000Z
We derive a general mean-field theory of inhomogeneous polymer dynamics; a theory whose form has been speculated and widely applied, but not heretofore derived. Our approach involves a functional integral representation of a Martin-Siggia-Rose (MSR) type description of the exact many-chain dynamics. A saddle point approximation to the generating functional, involving conditions where the MSR action is stationary with respect to a collective density field ? and a conjugate MSR response field ?, produces the desired dynamical mean-field theory. Besides clarifying the proper structure of mean-field theory out of equilibrium, our results have implications for numerical studies of polymer dynamics involving hybrid particle-field simulation techniques such as the single-chain in mean-field method.
Gluon condensation and deconfinement critical density in nuclear matter
M. Baldo; P. Castorina; D. Zappala'
2004-10-07T23:59:59.000Z
An upper limit to the critical density for the transition to the deconfined phase, at zero temperature, has been evaluated by analyzing the behavior of the gluon condensate in nuclear matter. Due to the non linear baryon density effects, the upper limit to the critical density, \\rho_c turns out about nine times the saturation density, rho_0 for the value of the gluon condensate in vacuum =0.012 GeV^4. For neutron matter \\rho_c \\simeq 8.5 \\rho_0. The dependence of the critical density on the value of the gluon condensate in vacuum is studied.
Barrett, Jeffrey A.
: University of Utah Press. 47-69. Part II: Importance of Dynamics Introduction to part II 1. Trust, Risk Jason Alexander) (1999) The Journal of Philosophy. 96: 588-598. 3. Stability and Explanatory Significance of Some Simple Evolutionary Models (2000) Philosophy of Science 67: 94-113. 4. Dynamics
Hartenstein, Reiner
Seminar NÂº 03301, Dynamically Reconfigurable Architectures A Mead-&-Conway-like Break Â·Ametek Â·Applied Dynamics Â·Astronautics Â·BBN Â·CDC Â·Convex Â·Cray Computer Â·Cray Research Â·Culler-Harris
Ji, Pengfei; Zhang, Yuwen, E-mail: zhangyu@missouri.edu [Department of Mechanical and Aerospace Engineering, University of Missouri, Columbia, Missouri 65211 (United States); Yang, Mo [College of Energy and Power Engineering, University of Shanghai for Science and Technology, Shanghai 200093 (China)
2013-12-21T23:59:59.000Z
The structural, dynamic, and vibrational properties during heat transfer process in Si/Ge superlattices are studied by analyzing the trajectories generated by the ab initio Car-Parrinello molecular dynamics simulation. The radial distribution functions and mean square displacements are calculated and further discussions are made to explain and probe the structural changes relating to the heat transfer phenomenon. Furthermore, the vibrational density of states of the two layers (Si/Ge) are computed and plotted to analyze the contributions of phonons with different frequencies to the heat conduction. Coherent heat conduction of the low frequency phonons is found and their contributions to facilitate heat transfer are confirmed. The Car-Parrinello molecular dynamics simulation outputs in the work show reasonable thermophysical results of the thermal energy transport process and shed light on the potential applications of treating the heat transfer in the superlattices of semiconductor materials from a quantum mechanical molecular dynamics simulation perspective.
Quantum-mechanical picture of peripheral chiral dynamics
Granados, C
2015-01-01T23:59:59.000Z
The nucleon's peripheral transverse charge and magnetization densities are computed in chiral effective field theory. The densities are represented in first-quantized form, as overlap integrals of chiral light-front wave functions describing the transition of the nucleon to soft pion-nucleon intermediate states. The orbital motion of the pion causes a large left-right asymmetry in a transversely polarized nucleon. The effect attests to the relativistic nature of chiral dynamics [pion momenta k = O(M_pi)] and could be observed in form factor measurements at low momentum transfer.
Quantum Dynamical Behaviour in Complex Systems - A Semiclassical Approach
Gliebe, Cheryn E; Ananth, Nandini
2008-05-22T23:59:59.000Z
One of the biggest challenges in Chemical Dynamics is describing the behavior of complex systems accurately. Classical MD simulations have evolved to a point where calculations involving thousands of atoms are routinely carried out. Capturing coherence, tunneling and other such quantum effects for these systems, however, has proven considerably harder. Semiclassical methods such as the Initial Value Representation (SC-IVR) provide a practical way to include quantum effects while still utilizing only classical trajectory information. For smaller systems, this method has been proven to be most effective, encouraging the hope that it can be extended to deal with a large number of degrees of freedom. Several variations upon the original idea of the SCIVR have been developed to help make these larger calculations more tractable; these range from the simplest, classical limit form, the Linearized IVR (LSC-IVR) to the quantum limit form, the Exact Forward-Backward version (EFB-IVR). In this thesis a method to tune between these limits is described which allows us to choose exactly which degrees of freedom we wish to treat in a more quantum mechanical fashion and to what extent. This formulation is called the Tuning IVR (TIVR). We further describe methodology being developed to evaluate the prefactor term that appears in the IVR formalism. The regular prefactor is composed of the Monodromy matrices (jacobians of the transformation from initial to finial coordinates and momenta) which are time evolved using the Hessian. Standard MD simulations require the potential surfaces and their gradients, but very rarely is there any information on the second derivative. We would like to be able to carry out the SC-IVR calculation without this information too. With this in mind a finite difference scheme to obtain the Hessian on-the-fly is proposed. Wealso apply the IVR formalism to a few problems of current interest. A method to obtain energy eigenvalues accurately for complex systems is described. We proposed the use of a semiclassical correction term to a preliminary quantum calculation using, for instance, a variational approach. This allows us to increase the accuracy significantly. Modeling Nonadiabatic dynamics has always been a challenge to classical simulations because the multi-state nature of the dynamics cannot be described accurately by the time evolution on a single average surface, as is the classical approach. We show that using the Meyer-Miller-Stock-Thoss (MMST) representation of the exact vibronic Hamiltonian in combination with the IVR allows us to accurately describe dynamics where the non Born-Oppenheimer regime. One final problem that we address is that of extending this method to the long time regime. We propose the use of a time independent sampling function in the Monte Carlo integration over the phase space of initial trajectory conditions. This allows us to better choose the regions of importance at the various points in time; by using more trajectories in the important regions, we show that the integration can be converged much easier. An algorithm based loosely on the methods of Diffusion Monte Carlo is developed that allows us to carry out this time dependent sampling in a most efficient manner.
Building a Universal Nuclear Energy Density Functional
Carlson, Joe A. [Michigan State University; Furnstahl, Dick; Horoi, Mihai; Lust, Rusty; Nazaewicc, Witek; Ng, Esmond; Thompson, Ian; Vary, James
2012-12-30T23:59:59.000Z
During the period of Dec. 1 2006 – Jun. 30, 2012, the UNEDF collaboration carried out a comprehensive study of all nuclei, based on the most accurate knowledge of the strong nuclear interaction, the most reliable theoretical approaches, the most advanced algorithms, and extensive computational resources, with a view towards scaling to the petaflop platforms and beyond. The long-term vision initiated with UNEDF is to arrive at a comprehensive, quantitative, and unified description of nuclei and their reactions, grounded in the fundamental interactions between the constituent nucleons. We seek to replace current phenomenological models of nuclear structure and reactions with a well-founded microscopic theory that delivers maximum predictive power with well-quantified uncertainties. Specifically, the mission of this project has been three-fold: ? First, to find an optimal energy density functional (EDF) using all our knowledge of the nucleonic Hamiltonian and basic nuclear properties; ? Second, to apply the EDF theory and its extensions to validate the functional using all the available relevant nuclear structure and reaction data; ? Third, to apply the validated theory to properties of interest that cannot be measured, in particular the properties needed for reaction theory.
Balanced homodyne detectors and Casimir energy densities
P. Marecki
2008-03-22T23:59:59.000Z
We recall and generalize the analysis of the output of the so-called balanced homodyne detectors. The most important feature of these detectors is their ability to quantify the vacuum fluctuations of the electric field, that is expectation values of products of (quantum-) electric-field operators. More precisely, the output of BHDs provides information on the one- and two-point functions of arbitrary states of quantum fields. We generalize the analysis of the response of BHDs to the case of quantum fields under influence of static external conditions such as cavities or polarizable media. By recalling the expressions for two-point functions of quantum fields in Casimir geometries we show, that a rich, position- and frequency-dependent pattern of BHD responses is predicted for ground states. This points to a potentially new characterization of quantum fields in Casimir setups which would not only complement the current global methods (Casimir forces), but also improve understanding of sub-vacuum energy densities present in some regions in these geometries.
Operator pencils on the algebra of densities
A. Biggs; H. M. Khudaverdian
2014-10-15T23:59:59.000Z
In this paper we continue to study equivariant pencil liftings and differential operators on the algebra of densities. We emphasize the role that the geometry of the extended manifold plays. Firstly we consider basic examples. We give a projective line of diff($M$)-equivariant pencil liftings for first order operators, and the canonical second order self-adjoint lifting. Secondly we study pencil liftings equivariant with respect to volume preserving transformations. This helps to understand the role of self-adjointness for the canonical pencils. Then we introduce the Duval-Lecomte-Ovsienko (DLO)-pencil lifting which is derived from the full symbol calculus of projective quantisation. We use the DLO-pencil lifting to describe all regular proj-equivariant pencil liftings. In particular the comparison of these pencils with the canonical pencil for second order operators leads to objects related to the Schwarzian. Within this paper the question of whether the pencil lifting factors through a full symbol map naturally arises.
Dynamics of laser-produced Sn-based plasmas for a monochromatic 13.5 nm extreme ultraviolet source
Najmabadi, Farrokh
the critical density, a narrower EUV x-ray spectrum and a higher conversion efficiency from laserDynamics of laser-produced Sn-based plasmas for a monochromatic 13.5 nm extreme ultraviolet source-0417 ABSTRACT Dynamics of laser-produced Sn-based plasmas were investigated for a monochromatic EUV lithography
The discontinuous dynamics and non-autonomous chaos
M. U. Akhmet
2007-12-31T23:59:59.000Z
A multidimensional chaos is generated by a special initial value problem for the non-autonomous impulsive differential equation. The existence of a chaotic attractor is shown, where density of periodic solutions, sensitivity of solutions and existence of a trajectory dense in the set of all orbits are observed. The chaotic properties of all solutions are discussed. An appropriate example is constructed, where the intermittency phenomenon is indicated. The results of the paper are illustrating that impulsive differential equations may play a special role in the investigation of the complex behavior of dynamical systems, different from that played by continuous dynamics.
Los Alamos Dynamics Summer School
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
School The Sixteenth Los Alamos Dynamics Summer School EXTENDED DEADLINES Los Alamos Dynamics Summer School Overview Contact Institute Director Charles Farrar (505) 663-5330...
Beam Dynamics for Induction Accelerators
Lee, E.P.
2014-01-01T23:59:59.000Z
Dynamics for Induction Accelerators Edward P. Lee Lawrencea natural candidate accelerator for a heavy ion fusion (HIF)words: Fusion, Induction, Accelerators, Dynamics This work
Studies in Nonlinear Dynamics & Econometrics
Studies in Nonlinear Dynamics & Econometrics Volume 8, Issue 3 2004 Article 1 The Long Memory in Nonlinear Dynamics & Econometrics is produced by The Berkeley Electronic Press (bepress). http
Dynamic Prediction of Concurrency Errors
Sadowski, Caitlin
2012-01-01T23:59:59.000Z
Relation 15 Must-Before Race Prediction 16 Implementation 17viii Abstract Dynamic Prediction of Concurrency Errors bySANTA CRUZ DYNAMIC PREDICTION OF CONCURRENCY ERRORS A
First principles molecular dynamics without self-consistent field optimization
Souvatzis, Petros, E-mail: petros.souvatsiz@fysik.uu.se [Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Box 516, SE-75120 Uppsala (Sweden)] [Department of Physics and Astronomy, Division of Materials Theory, Uppsala University, Box 516, SE-75120 Uppsala (Sweden); Niklasson, Anders M. N., E-mail: amn@lanl.gov [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)] [Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545 (United States)
2014-01-28T23:59:59.000Z
We present a first principles molecular dynamics approach that is based on time-reversible extended Lagrangian Born-Oppenheimer molecular dynamics [A. M. N. Niklasson, Phys. Rev. Lett. 100, 123004 (2008)] in the limit of vanishing self-consistent field optimization. The optimization-free dynamics keeps the computational cost to a minimum and typically provides molecular trajectories that closely follow the exact Born-Oppenheimer potential energy surface. Only one single diagonalization and Hamiltonian (or Fockian) construction are required in each integration time step. The proposed dynamics is derived for a general free-energy potential surface valid at finite electronic temperatures within hybrid density functional theory. Even in the event of irregular functional behavior that may cause a dynamical instability, the optimization-free limit represents a natural starting guess for force calculations that may require a more elaborate iterative electronic ground state optimization. Our optimization-free dynamics thus represents a flexible theoretical framework for a broad and general class of ab initio molecular dynamics simulations.
Dynamics and correlation length scales of a glass-forming liquid in quiescent and sheared conditions
Wen-Sheng Xu; Zhao-Yan Sun; Li-Jia An
2012-05-10T23:59:59.000Z
We numerically study dynamics and correlation length scales of a colloidal liquid in both quiescent and sheared conditions to further understand the origin of slow dynamics and dynamic heterogeneity in glass-forming systems. The simulation is performed in a weakly frustrated two-dimensional liquid, where locally preferred order is allowed to develop with increasing density. The four-point density correlations and bond-orientation correlations, which have been frequently used to capture dynamic and static length scales $\\xi$ in a quiescent condition, can be readily extended to a system under steady shear in this case. In the absence of shear, we confirmed the previous findings that the dynamic slowing down accompanies the development of dynamic heterogeneity. The dynamic and static length scales increase with $\\alpha$-relaxation time $\\tau_{\\alpha}$ as power-law $\\xi\\sim\\tau_{\\alpha}^{\\mu}$ with $\\mu>0$. In the presence of shear, both viscosity and $\\tau_{\\alpha}$ have power-law dependence on shear rate in the marked shear thinning regime. However, dependence of correlation lengths cannot be described by power laws in the same regime. Furthermore, the relation $\\xi\\sim\\tau_{\\alpha}^{\\mu}$ between length scales and dynamics holds for not too strong shear where thermal fluctuations and external forces are both important in determining the properties of dense liquids. Thus, our results demonstrate a link between slow dynamics and structure in glass-forming liquids even under nonequilibrium conditions.
Structure and dynamics of colloidal depletion gels: coincidence of transitions and heterogeneity
C. J. Dibble; M. Kogan; M. J. Solomon
2006-06-06T23:59:59.000Z
Transitions in structural heterogeneity of colloidal depletion gels formed through short-range attractive interactions are correlated with their dynamical arrest. The system is a density and refractive index matched suspension of 0.20 volume fraction poly(methyl methacyrlate) colloids with the non-adsorbing depletant polystyrene added at a size ratio of depletant to colloid of 0.043. As the strength of the short-range attractive interaction is increased, clusters become increasingly structurally heterogeneous, as characterized by number-density fluctuations, and dynamically immobilized, as characterized by the single-particle mean-squared displacement. The number of free colloids in the suspension also progressively declines. As an immobile cluster to gel transition is traversed, structural heterogeneity abruptly decreases. Simultaneously, the mean single-particle dynamics saturates at a localization length on the order of the short-range attractive potential range. Both immobile cluster and gel regimes show dynamical heterogeneity. Non-Gaussian distributions of single particle displacements reveal enhanced populations of dynamical trajectories localized on two different length scales. Similar dependencies of number density fluctuations, free particle number and dynamical length scales on the order of the range of short-range attraction suggests a collective structural origin of dynamic heterogeneity in colloidal gels.
The nucleation process and the roles of structure and density fluctuations in supercooled liquid Fe
Li, Rong; Wu, Yongquan, E-mail: yqwu@shu.edu.cn; Xiao, Junjiang [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China)] [Shanghai Key Laboratory of Modern Metallurgy and Materials Processing, Shanghai University, Shanghai 200072 (China)
2014-01-21T23:59:59.000Z
We observed homogeneous nucleation process of supercooled liquid Fe by molecular dynamics simulations. Using bond-orientational order parameters together with Voronoi polyhedron method, we characterized local structure, calculated the volume of Voronoi polyhedra of atoms and identified the structure and density fluctuations. We monitored the formation of nucleus and analyzed its inner structure. The birth and growth of the pre-nucleus and nucleus are accompanied with aggregating and disaggregating processes in the time scale of femtosecond. Only the initial solid-like clusters (ISLC), ranging from 1 to 7 atoms, pop up directly from liquid. The relation between the logarithm of number of clusters and the cluster size was found to be linear for ISLCs and was observed to be parabolic for all solid-like clusters (SLC) due to aggregating and disaggregating effects. The nucleus and pre-nuclei mainly consist of body centered cubic (BCC) and hexagonal close packed atoms, while the BCC atoms tend to be located at the surface. Medium-range structure fluctuations induce the birth of ISLCs, benefit the aggregation of embryos and remarkably promote the nucleation. But density fluctuations contribute little to nucleation. The lifetime of most icosahedral-like atoms (ICO) is shorter than 0.7 ps. No obvious relationship was found between structure/density fluctuations and the appearance of ICO atoms.
Systematic Density Expansion of the Lyapunov Exponents for a Two-dimensional Random Lorentz Gas
H. V. Kruis; Debabrata Panja; Henk van Beijeren
2005-09-30T23:59:59.000Z
We study the Lyapunov exponents of a two-dimensional, random Lorentz gas at low density. The positive Lyapunov exponent may be obtained either by a direct analysis of the dynamics, or by the use of kinetic theory methods. To leading orders in the density of scatterers it is of the form $A_{0}\\tilde{n}\\ln\\tilde{n}+B_{0}\\tilde{n}$, where $A_{0}$ and $B_{0}$ are known constants and $\\tilde{n}$ is the number density of scatterers expressed in dimensionless units. In this paper, we find that through order $(\\tilde{n}^{2})$, the positive Lyapunov exponent is of the form $A_{0}\\tilde{n}\\ln\\tilde{n}+B_{0}\\tilde{n}+A_{1}\\tilde{n}^{2}\\ln\\tilde{n} +B_{1}\\tilde{n}^{2}$. Explicit numerical values of the new constants $A_{1}$ and $B_{1}$ are obtained by means of a systematic analysis. This takes into account, up to $O(\\tilde{n}^{2})$, the effects of {\\it all\\/} possible trajectories in two versions of the model; in one version overlapping scatterer configurations are allowed and in the other they are not.
Pion scattering and nuclear dynamics
Johnson, M.B.
1988-01-01T23:59:59.000Z
A phenomenological optical-model analysis of pion elastic scattering and single- and double-charge-exchange scattering to isobaric-analog states is reviewed. Interpretation of the optical-model parameters is briefly discussed, and several applications and extensions are considered. The applications include the study of various nuclear properties, including neutron deformation and surface-fluctuation contributions to the density. One promising extension for the near future would be to develop a microscopic approach based on powerful momentum-space methods brought to existence over the last decade. In this, the lowest-order optical potential as well as specific higher-order pieces would be worked out in terms of microscopic pion-nucleon and delta-nucleon interactions that can be determined within modern meson-theoretical frameworks. A second extension, of a more phenomenological nature, would use coupled-channel methods and shell-model wave functions to study dynamical nuclear correlations in pion double charge exchange. 35 refs., 11 figs., 1 tab.
Textured-surface quartz resonator fluid density and viscosity monitor
Martin, Stephen J. (Albuquerque, NM); Wiczer, James J. (Albuquerque, NM); Cernosek, Richard W. (Albuquerque, NM); Frye, Gregory C. (Cedar Crest, NM); Gebert, Charles T. (Albuquerque, NM); Casaus, Leonard (Bernalillo, NM); Mitchell, Mary A. (Tijeras, NM)
1998-08-25T23:59:59.000Z
A pair of thickness-shear mode resonators, one smooth and one with a textured surface, allows fluid density and viscosity to be independently resolved. A textured surface, either randomly rough or regularly patterned, leads to trapping of liquid at the device surface. The synchronous motion of this trapped liquid with the oscillating device surface allows the device to weigh the liquid; this leads to an additional response that depends on liquid density. This additional response enables a pair of devices, one smooth and one textured, to independently resolve liquid density and viscosity; the difference in responses determines the density while the smooth device determines the density-viscosity product, and thus, the pair determines both density and viscosity.
Fabio Leoni; Giancarlo Franzese
2014-06-08T23:59:59.000Z
Confinement can modify the dynamics, the thermodynamics and the structural properties of liquid water, the prototypical anomalous liquid. By considering a general anomalous liquid, suitable for globular proteins, colloids or liquid metals, we study by molecular dynamics simulations the effect of a solvophilic structured and a solvophobic unstructured wall on the phases, the crystal nucleation and the dynamics of the fluid. We find that at low temperatures the large density of the solvophilic wall induces a high-density, high-energy structure in the first layer ("tempting" effect). In turn, the first layer induces a "molding" effect on the second layer determining a structure with reduced energy and density, closer to the average density of the system. This low-density, low-energy structure propagates further through the layers by templating effect and can involve all the existing layers at the lowest temperatures investigated. Therefore, although the high-density, high-energy structure does not self-reproduce further than the first layer, the structured wall can have a long-range effect thanks to a sequence of templating, molding and templating effects through the layers. We find dynamical slowing down of the solvent near the solvophilic wall but with largely heterogeneous dynamics near the wall due to superdiffusive liquid veins within a frozen matrix of solvent. Hence, the partial freezing of the first hydration layer does not correspond necessarily to an effective reduction of the channel section in terms of transport properties.
november 2011 Dynamic Ear | Home Helper
Papautsky, Ian
or narrow spaces are often impassable with wheels and legs, the ability of snakes to traverse at the University of Cincinnati. William Ball, MD Interim Vice President for Research Editor middle ear, 20 times its size 6 The Comfort of Home Students create a home- based system for seniors 8
Method for measuring the density of lightweight materials
Snow, Samuel G. (Oak Ridge, TN); Giacomelli, Edward J. (Knoxville, TN)
1980-01-01T23:59:59.000Z
This invention relates to a nondestructive method for measuring the density of articles composed of elements having a low atomic number such as plastic and carbon composites. The measurement is accomplished by striking the article with a collimated beam of X radiation, simultaneously monitoring the radiation scattered and the radiation transmitted by the article, then relating the ratio of the radiation scattered to the radiation transmitted with the density of the article. The above method is insensitive to all variables except density.
Crystallization of polyethylene by modified weighted density approximation(MWDA)
Razeghizadeh, Alireza; Lavafpour, Farhad
2015-01-01T23:59:59.000Z
In this article, we use the modified weighted density approximation to study the crystallization of polyethylene. We also use a direct correlation function of polyethylene based on RISM theory. The free energy of a polyethylene is calculated using density functional theory. The crystallization and solid and liquid density are calculated and finally compared with the prism simulation and experimental results. That shown the result obtained by MWDA is in better agreement, compared with the experimental result than the prism.
Crystallization of polyethylene by modified weighted density approximation(MWDA)
Alireza Razeghizadeh; Vahdat Rafee; Farhad Lavafpour
2015-02-07T23:59:59.000Z
In this article, we use the modified weighted density approximation to study the crystallization of polyethylene. We also use a direct correlation function of polyethylene based on RISM theory. The free energy of a polyethylene is calculated using density functional theory. The crystallization and solid and liquid density are calculated and finally compared with the prism simulation and experimental results. That shown the result obtained by MWDA is in better agreement, compared with the experimental result than the prism.
Particle-Number Projection and the Density Functional Theory
J. Dobaczewski; M. V. Stoitsov; W. Nazarewicz; P. -G. Reinhard
2007-08-03T23:59:59.000Z
In the framework of the Density Functional Theory for superconductors, we study the restoration of the particle number symmetry by means of the projection technique. Conceptual problems are outlined and numerical difficulties are discussed. Both are related to the fact that neither the many-body Hamiltonian nor the wave function of the system appear explicitly in the Density Functional Theory. Similar obstacles are encountered in self-consistent theories utilizing density-dependent effective interactions.