First Principles Calculations of Bulk, Surface and Extrinsic Properties of Crystals.

Ft. Belvoir Defense Technical Information Center JUN 1975.

18 p.

APPROVED FOR PUBLIC RELEASE.

The core approximation suggested by Bonifacic and Huzinaga was coded into the crystal Hartree-Fock programs. Calculations were performed on diamond, including the carbon 1s core and excluding the 1s core but including in its place the model Hamiltonian proposed by Bonifacic and Huzinaga. Energy bands, Compton profiles, X-ray structure factors and the cohesive energy were compared in detail. The conclusions were that this core approximation is extremely successful. It should prove very useful in all future crystalline and thin film Hartree-Fock calculations. Thin film unrestricted Hartree-Fock programs were written for the (111) planes of diamond. The programs are in the final states of debugging. Preliminary experience indicates that the programs will be extremely expensive to run. Consequently, attention is currently being focussed on developing further techniques for speeding up the crystal and thin film programs. Excitation equations for many-body systems have been set up which show that a general description in terms of self-energy effects, such as relaxation and correlation, and particle-hole interactions is possible. If certain criteria are met, these equations take on a simple form. Calculations have been done on atomic Be and Ne and a good comparison with experiment was obtained. At present calculations are being set up for crystalline LiF. (Author).

English

February 07, 2011