Band structure, cohesive energy, optical conductivity, and Compton profile of lithium

Abstract

A self-consistent calculation of energy bands in lithium has been performed using the linear-combination-of-atomic-orbitals (LCAO) method. The basis set consisted of nine $s$-type, six $p$-type, and three $d$-type Gaussian orbitals. Exchange was included according to the $X\alpha$ method with $\alpha =\frac{2}{3}$. Results are presented for the band structure, Fermi-surface properties, cohesive energy, and the Compton profile. The interband contribution to the optical conductivity was calculated including the $\overrightarrow{\mathrm{k}}$ variation of the momentum matrix elements. The distortions of the Fermi surface from spherical symmetry are less than 4%. The optical and thermal effective-mass ratios are 1.48 and 1.53, respectively. The onset of direct interband transitions is predicted to occur at 3.28 eV. The calculated cohesive energy is 0.124 Ry.