## Benchmarking Electronic Structure Methods for Accurate Fixed-Charge Electrostatic Models

dataset

posted on 19.12.2019, 18:43 by Alex Zhou, Michael Schauperl, Paul S. NerenbergThe 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 (HF) 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 methodsor ones similar to themshould be adopted
for the derivation of accurate partial atomic charges for next-generation
MM force fields.