Electronic structure studies of solids. IV. Physical quantities from rigorous Hartree-Fock results for lithium crystals

Abstract

Quantities associated with soft X-ray emission, the work function, the pseudopotential and Compton profiles for body centred cubic (b.c.c.) and face centred cubic (f.c.c.) lithium crystals have been calculated in the Hartree-Fock approximation of Kumar, Monkhorst and Harris (Phys. Rev. B1974). The width of the occupied part of the valence band is calculated too large by about 3 eV. Combination of soft X-ray emission and work function data indicates the bottom of the valence band is at nearly the correct position. It is found that the energy dependence of the transition dipole matrix element cannot explain prepeaking below the Fermi edge of the soft X-ray line shape. A pseudopotential form factor v(q) is calculated in the on Fermi sphere approximation. Comparison with an 'experimental' pseudopotential reflects the importance of correlation effects for small q values and the correct lattice spacing for large q values.