Electronic Band Structure of Gray Tin

The electronic energy band structure including spin-orbit coupling effects has been calculated for semiconducting gray tin. The orthogonalized plane-wave method has been used to obtain the energy eigenvalues at the symmetry points $\Gamma$, $X$, and $L$ in the Brillouin zone and to compute the spin-orbit splittings at these points. It is found that both the conduction and valence band edges are at the center of the zone. The effective masses for electrons and holes are calculated using our crystal wavefunctions and the experimental value for the energy gap. The effect of pressure on the energy band structure is also investigated.