Are Multiatom Interactions Relevant for the Determination of Stability of Ordered Structures and Short Range Order in Binary Transition Metal Alloys?

Abstract

The role of multiatom interactions in determining both the stability of ordered structures in the ground state and the short range order, occurring in transition metal alloys, has been investigated by means of the generalized perturbation method discussed previously. This method enables to compute the multiatom interactions from the electronic structure; as a result of the angular dependence of the transfer integrals it is shown that, contrarily to what is generally believed, the most important interactions, coming from “d” bands, are not those corresponding to the most compact clusters (triangles, tetrahedrons…) but to straight self-retraced paths. However the pair approximation is generally valid for the study of stability as long as no self-retraced paths, connecting neighbouring minority atoms, occur in the ordered structures and provided the concentration dependence of the pair interactions is taken into account. An expression of the configurational energy in terms of irreducible two and three body interactions is given.