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Title: Breakdown of classical electrostatics in the depolarization of quantum wires and nanotubes

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Journal Article: Publisher's Accepted Manuscript
Journal Name:
Physical Review B
Additional Journal Information:
Journal Volume: 96; Journal Issue: 19; Related Information: CHORUS Timestamp: 2017-11-30 10:03:57; Journal ID: ISSN 2469-9950
American Physical Society
Country of Publication:
United States

Citation Formats

Shan, L., and Mishchenko, E. G. Breakdown of classical electrostatics in the depolarization of quantum wires and nanotubes. United States: N. p., 2017. Web. doi:10.1103/PhysRevB.96.195441.
Shan, L., & Mishchenko, E. G. Breakdown of classical electrostatics in the depolarization of quantum wires and nanotubes. United States. doi:10.1103/PhysRevB.96.195441.
Shan, L., and Mishchenko, E. G. 2017. "Breakdown of classical electrostatics in the depolarization of quantum wires and nanotubes". United States. doi:10.1103/PhysRevB.96.195441.
title = {Breakdown of classical electrostatics in the depolarization of quantum wires and nanotubes},
author = {Shan, L. and Mishchenko, E. G.},
abstractNote = {},
doi = {10.1103/PhysRevB.96.195441},
journal = {Physical Review B},
number = 19,
volume = 96,
place = {United States},
year = 2017,
month =

Journal Article:
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This content will become publicly available on November 30, 2018
Publisher's Accepted Manuscript

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  • We performed the resistively-detected nuclear magnetic resonance (RDNMR) to study the electron spin polarization in the non-equilibrium quantum Hall regime. By measuring the Knight shift, we derive source-drain bias voltage dependence of the electron spin polarization in quantum wires. The electron spin polarization shows minimum value around the threshold voltage of the dynamic nuclear polarization.
  • We present a theoretical model of the quantum decoherence experienced by a pair of polarization-entangled photons, after one of them is sent through a nanohole array, and compare this with the classical depolarization experienced by light with a fixed polarization when this is sent through the same array. We discuss the conditions under which the quantum visibility and the classical degree of polarization are the same. Experimental verification is done with arrays of square and hexagonal symmetry.
  • A transient interference during the collision of a broad quantum particle wave packet with a properly chosen potential barrier suppresses, for energies well above the barrier top, the main incident momentum. This collision enhances the momenta below and above the central one, violating the classical conservation of energy. For the double square barrier the effect is due to the interference between three components (incident, transmitted, and interbarriers terms) and survives much longer than for the single barrier, facilitating its observation. A quantum optical realization with two-level atoms and effective laser barriers is discussed.
  • The Wolf summation approach [D. Wolf et al., J. Chem. Phys. 110, 8254 (1999)], in the damped shifted force (DSF) formalism [C. J. Fennell and J. D. Gezelter, J. Chem. Phys. 124, 234104 (2006)], is extended for treating electrostatics in combined quantum mechanical and molecular mechanical (QM/MM) molecular dynamics simulations. In this development, we split the QM/MM electrostatic potential energy function into the conventional Coulomb r{sup −1} term and a term that contains the DSF contribution. The former is handled by the standard machinery of cutoff-based QM/MM simulations whereas the latter is incorporated into the QM/MM interaction Hamiltonian as amore » Fock matrix correction. We tested the resulting QM/MM-DSF method for two solution-phase reactions, i.e., the association of ammonium and chloride ions and a symmetric SN{sub 2} reaction in which a methyl group is exchanged between two chloride ions. The performance of the QM/MM-DSF method was assessed by comparing the potential of mean force (PMF) profiles with those from the QM/MM-Ewald and QM/MM-isotropic periodic sum (IPS) methods, both of which include long-range electrostatics explicitly. For ion association, the QM/MM-DSF method successfully eliminates the artificial free energy drift observed in the QM/MM-Cutoff simulations, in a remarkable agreement with the two long-range-containing methods. For the SN{sub 2} reaction, the free energy of activation obtained by the QM/MM-DSF method agrees well with both the QM/MM-Ewald and QM/MM-IPS results. The latter, however, requires a greater cutoff distance than QM/MM-DSF for a proper convergence of the PMF. Avoiding time-consuming lattice summation, the QM/MM-DSF method yields a 55% reduction in computational cost compared with the QM/MM-Ewald method. These results suggest that, in addition to QM/MM-IPS, the QM/MM-DSF method may serve as another efficient and accurate alternative to QM/MM-Ewald for treating electrostatics in condensed-phase simulations of chemical reactions.« less