Equations of state for strongly anharmonic crystals with a complex lattice

On the basis of a nonsymmetrized self-consistent-field approximation, thermal and caloric equations of state for strongly anharmonic crystals with a complex lattice are considered, allowing, in principle, anharmonism of any desired (basically, even) order to be taken into account. These equations include the moments of single-particle distribution functions, which are the solutions of some system of transcendental equations. More detailed consideration is given to the case of binary crystals with strong fourth-order anharmonism. The possibility of obtaining corrections to the approximation adopted is also discussed. © 1980 Plenum Publishing Corporation.