Polarizable Model Potential Function for Ion−Methanol Systems

Abstract

A polarizable model potential (PMP) function for methanol and three ions (Cl-, Na+, and Mg2+) is developed on the basis of high-level ab initio molecular orbital calculations (MP2/6-311++G(2d,2p)). The PMP function consists of Coulomb, polarization, and Lennard-Jones terms. The permanent partial charge parameters of the Coulomb term, and the multicenter polarizability parameters of the polarization term, are determined by using electrostatic potential optimization, and polarizable one-electron potential (POP) optimization, respectively. The Lennard-Jones parameters are adjusted to reproduce the ab initio potential energy surfaces of methanol dimer and ion−methanol complexes. The PMP function using the final parameters reproduced well the ab initio energy surfaces of methanol dimer, ion−methanol, and methanol−ion−methanol systems. The root-mean-square (rms) deviations of ion−methanol systems having various conformations are only 10−12% of the ab initio interaction energies. The electron density changes by ...