Electronic Structure Studies of Solids. IV. Physical Quantities from Rigorous Hartree-Fock Results for Lithium Crystals.

摘要

Quantities associated with soft x ray emission, the work function, the pseudo-potential and Compton profiles for body centred cubic (bcc) and face centred cubic (fcc) lithium crystals have been calculated in the Hartree-Fock approximation of Kumar, Monkhorst and Harris. 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. Correlation effects account for a 1 to 2 eV decrease of the onset of the soft x ray emission. 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 correlations effects for small q values and the correct lattice spacing for large q values. It is found that at least half the difference between the free electron and experimental Compton profiles is due to band structure effects. Only a small difference between fcc and bcc profiles is predicted. (Author)