Pair potential for alkali metal halides with rock salt crystal structure. Molecular Dynamics Calculations on NaCl and LiI

Abstract

A new effective pair potential is proposed. This potential is based on the thermodynamic properties of alkali metal halides in the crystal phase and takes into account the pressure dependence of the compressibility. The form of the new potential is; ϕ(r_ij)=+ [graphic omitted] + [graphic omitted] exp[–k(r^m_ij–r^m_0ij)]– [graphic omitted] – [graphic omitted]. The values of b and k are given for several values of n and m. The effective pair potential with n= 4 and m= 1 has been preferred for reasons given in this paper.

MD-calculations are performed with the new effective pair potential on NaCl and on LiI. The results indicate that this new effective pair potential is a substantial improvement as compared with the widely used potential proposed by Tosi and Fumi, and also as compared with the gas phase potential developed by Woodcock.