Electron energy levels in LaSn3. I. Nonrelativistic modified orthogonalized-plane-wave calculation

Electron energy levels in perfectly ordered LaSn₃ have been calculated nonrelativistically for the equivalent of 64 points in the reciprocal-space lattice using a modified orthogonalized-plane-wave method (MOPW). A muffin-tin model potential, constructed from the self-consistent nonrelativistic atomic potentials of Herman and Skillman, is used. The crystal calculation is not self-consistent. E(k⃗) curves are shown for six directions in k⃗ space. The nonrelativistic Fermi level has been computed to be - 0. 47 Ry. Calculations were also carried out for a limited number of points using a potential constructed from the self-consistent relativistic atomic potentials of Liberman. Differences between the levels resulting from this potential and the levels resulting from the Herman-Skillman-based potential are discussed. In a separate paper, perturbation theory is used to determine relativistic corrections to the Herman-Skillman-based levels.