Evaluation of isomorphous models of alloys

Abstract

Order-$N$ methods for calculating the electronic structure of clusters containing hundreds of atoms using realistic self-consistent density-functional theory local-density approximation potentials make it possible to test alloy theories more definitively. Tests are carried out on isomorphous models of alloys in which the atoms of each species are treated as identical. In contrast, the order-$N$ calculations lead to a polymorphous model in which all of the atoms are unique. Isomorphous models are seen to reproduce average densities of states and cohesive energies surprisingly well, in spite of their deficiencies in other areas.