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Benchmarking Electronic Structure Methods for Accurate Fixed-Charge Electrostatic Models

preprint
revised on 22.11.2019, 21:18 and posted on 29.11.2019, 18:22 by Alex Zhou, Michael Schauperl, Paul Nerenberg

The accuracy of classical molecular mechanics (MM) force fields used for condensed phase molecular simulations depends strongly on the accuracy of modeling nonbonded interactions between atoms, such as electrostatic interactions. Some popular fixed-charge MM force fields use partial atomic charges derived from gas phase electronic structure calculations using the Hartree-Fock method with the relatively small 6-31G* basis set (HF/6-31G*). It is generally believed that HF/6-31G* generates fortuitously overpolarized electron distributions, as would be expected in the higher dielectric environment of the condensed phase. Using a benchmark set of 47 molecules we show that HF/6-31G* overpolarizes molecules by just under 10% on average with respect to experimental gas phase dipole moments. The overpolarization of this method/basis set combination varies significantly though and, in some cases, even leads to molecular dipole moments that are lower than experimental gas phase measurements. We further demonstrate that using computationally inexpensive density functional theory (DFT) methods, together with appropriate augmented basis sets and a continuum solvent model, can yield molecular dipole moments that are both more strongly and more uniformly overpolarized. These data suggest that these methods – or ones similar to them – should be adopted for the derivation of accurate partial atomic charges for next-generation MM force fields.

Funding

CALIFORNIA STATE UNIVERSITY LOS ANGELES PROPOSES TO ESTABLISH A NASA DATA INTENSIVE RESEARCH AND EDUCATION CENTER IN STEM DIRECT STEM TO CONDUCT COLLABORATIVE RESEARCH AND TRAINING IN AREAS OF HYDROLOGY AND CLIMATE CHANGE COMPUTATIONAL PHYSICS AND CLOUD C

National Aeronautics and Space Administration

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Efficient, Polarizable Charge Model for Molecular Simulation

FWF Austrian Science Fund

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History

Email Address of Submitting Author

pnerenb@calstatela.edu

Institution

California State University, Los Angeles

Country

United States

ORCID For Submitting Author

0000-0002-9730-6983

Declaration of Conflict of Interest

No conflict of interest.

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in Journal of Chemical Information and Modeling

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