Iterative fluctuation charge model: A new variable charge molecular dynamics method

Abstract

In molecular simulations, calculation of environmentally dependent atomic charges is still a demanding task. Empirical and semiempirical methods have been proposed and applied to a wide range of problems with different success. In this paper, a new scheme based on the concept of electronegativity equalization is presented and its advantages over several other methods are discussed. This method is an extension of the fluctuation charge model [S. W. Rick, S. J. Stuart, and B. J. Berne, J. Chem. Phys. 101, 6141 (1994)]. By allowing multiple electronic iterations at each nuclear step, the condition of electronegativity equalization can be satisfied to a selected precision. Molecular dynamics simulations using this new method, as well as several other methods, are performed on α quartz. Analysis of the simulated results shows that it is advantageous to use the iterative fluctuation charge model in several different situations. © 2006 American Institute of Physics.