General Model for Treating Short-Range ElectrostaticPenetration in a Molecular Mechanics Force Field

摘要

Classical molecular mechanics force fields typically model interatomic electrostatic interactions with point charges or multipole expansions, which can fail for atoms in close contact due to the lack of a description of penetration effects between their electron clouds. These short-range penetration effects can be significant and are essential for accurate modeling of intermolecular interactions. In this work we report parametrization of an empirical charge–charge function previously reported (Piquemal J.-P.; et al.J. Phys. Chem. A 2003, 107, 10353. [] []) to correct for the missing penetration term in standard molecular mechanics force fields. For this purpose, we have developed a database (S101×7) of 101 unique molecular dimers, each at 7 different intermolecular distances. Electrostatic, induction/polarization, repulsion, and dispersion energies, as well as the total interaction energy for each complex in the database are calculated using the SAPT2+ method (Parker T. M.; et al.J. Chem. Phys. 2014, 140, 094106 [] []). This empirical penetration modelsignificantly improves agreement between point multipole and quantummechanical electrostatic energies across the set of dimers and distances,while using only a limited set of parameters for each chemical element.Given the simplicity and effectiveness of the model, we expect theelectrostatic penetration correction will become a standard componentof future molecular mechanics force fields.