A cluster expansion of the internal energy is carried out for a phase comprised of sublattices which have different coordination numbers, and the equation for the mixing energy is derived. The resultant expression of the mixing energy is equivalent to that derived using the higher‐order approximation of the Bond Energy Model. It is shown that the effective pair interaction energy of the cluster expansion is exactly the site exchangc energy of the Bond Energy Model. The cluster expansion method is suitable for use in higher‐order approximation calculations of the free energy.
ASJC Scopus subject areas
- Electronic, Optical and Magnetic Materials
- Condensed Matter Physics