EFFECT OF OVERLAP OF LOCALIZED ORBITALS ON THE BAND-STRUCTURE OF INSULATORS UNDER PRESSURE

A new method for calculating the energy spectra of compressed insulato rs based on the cluster expansion is proposed. The dependence on the c ompression of the spectra of both the conduction band and the valence bands is uniquely determined by the values of the overlap integrals of the orbitals of pairs of isolated atoms. The overlap integrals and th e matrices defined by them are calculated numerically for inert-gas cr ystals and their properties and values are analyzed for different latt ice constants. Numerical calculations of the bands of the compressed c rystal in the various proposed models are carried out and discussed fo r neon. (C) 1998 American Institute of Physics. [S1063-7834(98)01508-1 ].