Electron Energy Levels in LaSn3. I. A Nonrelativistic Modified Orthogonalized-Plane-Wave Calculation

Electron energy levels in perfectly ordered La${\mathrm{Sn}}_3$ 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. $E\left(\overrightarrow{\mathrm{k}}\right)$ curves are shown for six directions in $\overrightarrow{\mathrm{k}}$ 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.