Cluster expansion approach for modeling strain effects on alloy phase stability

We demonstrate applicability of the proposed extended cluster expansion (CE) technique, enabling complete representation of strain effects on alloy configurational energy on single and multiple lattices. Complete and orthonormal basis function to describe configurational energy is constructed in terms of spin variable ω on virtual lattice and σ on base lattice, where the former specifies the strain of a given cell from the base cell. We estimate formation energy of superlattice composed of alternate stacking of ordered structures for Cu–Au binary alloys where the strain effects should play significant role. The proposed CE is shown to precisely estimate the strain effects on total energy for alloys, which cannot be essentially handled by the current CE.