A simple environment-dependent overlap potential and Cauchy violation in solid argon

We develop an analytic and environment-dependent interatomic potential for the overlap repulsion in solid argon, based on an approximate treatment of the nonorthogonal tight-binding theory for closed-shell systems. The present model can reproduce the observed elastic properties of solid argon well, including the Cauchy violation at high pressures, yet it is very simple. A useful and novel analysis is given to show how the elastic properties are related to the environment dependence incorporated into a generic pairwise potential. The present study has a close link to the broad field of computational materials science, in which the inclusion of environment dependence in the short-ranged repulsive part of a potential model is sometimes crucial in predicting the elastic properties correctly.