A NEW APPROACH TO DERIVING INTERATOMIC MANY-BODY INTERACTIONS IN METALS

An original method of treating the kinetic and exchange-correlation en ergies functionals in terms of many particle interactions was develope d. It is based on utilising the local density approximation. The fetal electron density, extracted from the ab initio band structure calcula tions, is expressed as a linear superposition of contributions from th e individual pseudoions embedded in the uniform background. The explic it expressions for the pair and triplet potentials are presented. The general form for the part of the pair interatomic interactions caused by the kinetic and the exchange-correlation effects is obtained. Relat ionship between the developing approach and the perturbation theory in pseudopotential is analysed. Unlike the perturbation theory the advan ced approach allows one to calculate accurately the so-called reducibl e contributions to the pair potential arising from the n-particle (n > 2) interactions. It corresponds to summing certain series in pseudopo tential. Contribution of the electron-nonlocal pseudopotential interac tions to the pair interatomic ones is considered within the concept of the fully separable pseudopotentials.