An explicit link was established between 2 types of ab initio statistical mechanics methods for ordered compounds. These were the single-defect theory, which was used for low defect concentrations, and the cluster-expansion technique which was used for high defect concentrations. It was shown how the single defect theory could be extended by including elastic interaction effects between various defects.

Ab Initio Statistical Mechanics for Ordered Compounds - Single-Defect Theory versus Cluster-Expansion Techniques. R.Drautz, I.Schultz, F.Lechermann, M.Fähnle: Physica Status Solidi B, 2003, 240[1], 37-44