Mechanical stability criteria for interatomic potential functions used in computer simulations of materials

A static method is presented for investigating the mechanical stability of interatomic potential functions used in computer simulations of material systems. The potential functions are assumed to be composed of a pair interatomic potential term and a density dependent term. Two minimal criteria for potential functions are proposed: the correct prediction of the stable crystal structure and lattice constant. The method is applied to a number of commonly used pair potential functions. Some of these pair potential functions do not satisfy the minimal criteria. A linear volume term was added to these potential functions resulting in improvement in some cases. In other cases even the modified potential functions do not satisfy the above mentioned minimal requirements.