Two Improved Electronegativity Equalization Methods for Charge Distribution in Large Scale Non-Uniform System.

Nowadays, molecular dynamics (MD) using force fields has become an effective tool for physical and chemical problems. In the MD method, the classical Electronegativity Equalization Method (EEM) is widely accepted for atom charge computing, which may result in unreasonable predictions for large scale non-uniform systems. In order to improve the accuracy of charge computing in MD simulations, two versions of improved EEM for charge distribution calculation are proposed in the present work, without introducing new empirical parameters, namely the locally equilibrated EEM and the sub-zone EEM. The aim of the proposed methods is to eliminate the unreasonable interaction of the long-range charge in large scale non-uniform systems. Comparison between the two improved EEMs and the original EEM in both uniform and non-uniform systems shows that both the improved EEMs successfully eliminate the effect of the unreasonable long-range charge interaction which is inevitably encountered in the original EEM.