Application of the optimized model potential to calculation of energy-wave-number characteristics for simple metals

Abstract

The optimized model potential proposed by Shaw is applied to the problem of determining band-structure energies for simple metals. Expressions for the structure-dependent contributions to the total energy are derived in Hartree approximation. The derivation is similar to that given by Harrison for pseudopotentials, but has several features which are unique to model potentials. It is shown that the separation of structure-dependent contributions into electrostatic and band-structure energies is not unique and that the choice of effective valence is therefore arbitrary. An expression for the energy-wave-number characteristic is given in terms of the optimized model potential, and is evaluated as a function of scattering momentum for eight simple metals. A comparison is made between results obtained from the full nonlocal theory and those from various local approximations. The results for the energy-wave-number characteristic are used to calculate effective ion-ion interactions and to predict stable crystal structures.