Hardness and softness in the ab initio study of polyatomic systems

A combination of the maximum hardness (MH) principle, and the local version of the hard and soft acids and bases (HSAB) principle is tested as a tool to describe the stability and reactivity of polyatomic systems. The local HSAB principle describes regional differences in reactivity whereas the MH principle selects the most stable configuration. This approach is tested using ab initio density functional theory techniques. Total-energy calculations fully confirm the validity of both principles.