Crystal Potentials and the Fermi Surface of the Alkali Metals (I)

Fermi surfaces of all alkali metals are evaluated by A.P.W. method with various crystal potentials, which include the Wigner-Seitz potential, Hartree-Fock-Slater self-consistent crystal potential and the Heine-Hedin type potential. The results are compared with available experiments. The purpose of the calculation is to examine the accuracy of the ab initio calculation to reproduce the observed Fermi surface, and also to examine what potential is the best. It is found that the original Wigner-Seitz potential is a fairly good potential, but not the best one. It is suggested that the best potential should include the effects of the crystal.