A classical theory of concentrated solid solutions

Using Mayer's virial series for an inhomogeneous system, a classical theory of solid solution is constructed. The long-standing problem of incorporating vibrations in the lattice gas model is resolved, at least partially. In addition, thermal expansion, anharmonicity and vacancies are taken into account. In spite of all these factors, the mathematics are still tractable. This is possible because the equilibrium densities of particles are assumed to differ appreciably from zero only in the immediate vicinity of equilibrium positions, i.e. the particles of a solid are localized. One of the interesting results of the present investigation is that the formation entropy per vacancy is equal to 1.5 k B , a fact confirmed by some experiments.