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Title: The Flexible, Polarizable, Thole-Type Interaction Potential for Water (TTM2-F) Revisited

Authors:
;
Publication Date:
Research Org.:
Environmental Molecular Sciences Laboratory (EMSL)
Sponsoring Org.:
USDOE Office of Science (SC), Biological and Environmental Research (BER)
OSTI Identifier:
1152413
Resource Type:
Journal Article
Resource Relation:
Journal Name: The Journal of Physical Chemistry A; Journal Volume: 110; Journal Issue: 11
Country of Publication:
United States
Language:
English

Citation Formats

George S.,Fanourgakis, and Sotiris S.,Xantheas. The Flexible, Polarizable, Thole-Type Interaction Potential for Water (TTM2-F) Revisited. United States: N. p., 2006. Web. doi:10.1021/jp056477k.
George S.,Fanourgakis, & Sotiris S.,Xantheas. The Flexible, Polarizable, Thole-Type Interaction Potential for Water (TTM2-F) Revisited. United States. doi:10.1021/jp056477k.
George S.,Fanourgakis, and Sotiris S.,Xantheas. Wed . "The Flexible, Polarizable, Thole-Type Interaction Potential for Water (TTM2-F) Revisited". United States. doi:10.1021/jp056477k.
@article{osti_1152413,
title = {The Flexible, Polarizable, Thole-Type Interaction Potential for Water (TTM2-F) Revisited},
author = {George S.,Fanourgakis and Sotiris S.,Xantheas},
abstractNote = {},
doi = {10.1021/jp056477k},
journal = {The Journal of Physical Chemistry A},
number = 11,
volume = 110,
place = {United States},
year = {Wed Mar 01 00:00:00 EST 2006},
month = {Wed Mar 01 00:00:00 EST 2006}
}
  • We report classical molecular dynamics simulations of liquid water with a flexible, polarizable, Thole-type interaction potential. We report the radial distribution functions, average energy, internal geometry and dipole moment in the liquid as well as the density, dielectric constant and self-diffusion coefficient at T=300 K from (NVT) and (NPT) classical molecular dynamics simulations. In order to facilitate these simulations we have found it necessary to modify the original version of the TTM2-F potential [J. Chem. Phys. 116, 5115 (2002)] in order to consistently describe the fragment molecular dipole moment and alleviate problems arising at small intermolecular separations. Furthermore, the parallelmore » implementation of the revised version (TTM2.1-F) under periodic boundary conditions enables for the efficient calculation of the macroscopic structural and thermodynamic properties of liquid water as its performance scales superlinearly with number of processors for a 256 molecule periodic simulation box.« less
  • We present a new parametrization of the flexible, polarizable Thole-type model for water [J. Chem. Phys. 116, 5115 (2002); J. Phys. Chem. A 110, 4100 (2006)], with emphasis in describing the vibrational spectra of both water clusters and liquid water. The new model is able to produce results of similar quality with the previous versions for the structures and energetics of water clusters as well as structural and thermodynamic properties of liquid water evaluated with classical and converged quantum statistical mechanical atomistic simulations. At the same time it yields ­ for the first time for a classical interaction potential formore » water ­ accurate red shifts for the OH vibrational stretches of both water clusters and liquid water. This work was supported by the U.S. Department of Energy's (DOE) Office of Basic Energy Sciences, Chemical Sciences program. The Pacific Northwest National Laboratory is operated by Battelle for DOE.« less
  • In this work we examine the consequences of incorporating the ab-initio derived monomer potential energy surface and non-linear dipole surface of Partridge and Schwenke [J. Chem. Phys. 106, 4618 (1997)] into the previously developed TTM2-R model of Burnham et al. [J. Chem. Phys. xx. yyyy (2001)] in order to develop a new, all-atom polarizable, flexible model for water (TTM2-F). We found that the use of the non-linear dipole surface is essential in modeling the change in the internal geometry of interacting water molecules and, in particular, the increase in the internal H-O-H bend angle with cluster size. This is themore » first demonstration of a flexible model which shows an increase in the bending angle in clusters. An explanation for this behavior is presented using the concept of geometric polarizabilities . The model furthermore reproduces the n=2-6 cluster binding energies to within an RMS deviation of 0.05 kcal/mol per hydrogen bond with respect to the MP2 complete basis set estimates.« less
  • The aim of this work is to compute the stabilization energy E{sub stab}(n) of [X(H{sub 2}O){sub n}]{sup -} (X{identical_to}F, Br, and I for n=1-60) clusters from Monte Carlo simulations using first-principles ab initio potentials. Stabilization energy of [X(H{sub 2}O){sub n}]{sup -} clusters is defined as the difference between the vertical photodeachment energy of the cluster and the electron affinity of the isolated halide. On one hand, a study about the relation between cluster structure and the E{sub stab}(n) value, as well as the dependence of the latter with temperature is performed, on the other hand, a test on the reliabilitymore » of our recently developed first-principles halide ion-water interaction potentials is carried out. Two different approximations were applied: (1) the Koopmans' theorem and (2) calculation of the difference between the interaction energy of [X(H{sub 2}O){sub n}]{sup -} and [X(H{sub 2}O){sub n}] clusters using the same ab initio interaction potentials. The developed methodology allows for using the same interaction potentials in the case of the ionic and neutral clusters with the proviso that the charge of the halide anion was switched off in the latter. That is, no specific parametrization of the interaction potentials to fit the magnitude under study was done. The good agreement between our predicted E{sub stab}(n) and experimental data allows us to validate the first-principles interaction potentials developed elsewhere and used in this study, and supports the fact that this magnitude is mainly determined by electrostatic factors, which can be described by our interaction potentials. No relation between the value of E{sub stab}(n) and the structure of clusters has been found. The diversity of E{sub stab}(n) values found for different clusters with similar interaction energy indicates the need for statistical information to properly estimate the stabilization energy of the halide anions. The effect of temperature in the prediction of the E{sub stab}(n) is not significant as long as it was high enough to avoid cluster trapping into local equilibrium configurations which guarantees an appropriate sampling of the configurational space. Parallel tempering method was applied in particular cases to guarantee satisfactory sampling of clusters at low temperature.« less
  • The authors report a systematic study of the structure of small water clusters, up to pentamers, using a hybrid quantum-mechanics/molecular-mechanics approach with polarizable flexible water-interaction potentials in conjunction with HF SCF wave functions. The model is denoted QM/MM-pol-vib. For each optimized QM cluster, QM water molecules were replaced one at a time with MM-pol-vib water molecules and reoptimized the cluster structure. The hybrid structures and energies were found to reproduce well their full QM counterparts. This finding indicates that the first hydration shell of solvation obtained with such a model is described at a semiquantitative level of accuracy. The modelmore » should prove useful in modeling aqueous reactions. The efficient computational strategy adopted for coupling the polarizable response of the solvent with the solute wave function calculation was outlined. Energy gradients for the solute and the solvent molecules are also efficiently calculated.« less