Application of the hypervolume Monte Carlo methods to a molten ionic system

Abstract

The Hyper Volume Monte Carlo Method (HVMC) proposed by Fernandes and Ramalho initially developed for the NVE ensemble, has recently been extended to the NpH ensemble. The methods have been applied to simple molecular and magnetic systems. The purpose of this work is to apply the HVMC method to an ionic system in the NVE and NpH ensembles and to compare the results with a NVE molecular dynamics (MD) simulation. The Born–Mayer–Huggins pair potential with parameters for KCl has been used. The long range electrostatic interactions were calculated using the modified Ewald sum of Adams and Dubey (D. Adams, G. Dubey, CCP5 Newsletter 22 (1986) 39; D. Adams, G. Dubey, J. Comp. Phys. 72 (1987) 156). A molten KCl system at 1045, 1306, 2090 and 2874 K and at several densities has been studied using 216 ions. At 1306 K, a number-dependence analysis using 64, 216, 512 and 1000 ions has been performed. The thermodynamics averages obtained by NVE MD simulations were used as inputs for the HVMC method. The thermal, structural properties and speed distribution functions have been calculated and an excellent agreement has been found between the MD and the HVMC methods at different temperatures and numbers of ions.