Calculation of the band structure, Fermi surface, and interband optical conductivity of lithium

The band structure of lithium has been calculated by the OPW method using the Seitz potential for the ions and the selfconsistent Hartree potential due to the conduction electrons. Use of the same potential for the 'core state' as for the conduction-electron states is found to be of some importance. A novel method is presented to transform the OPW generalized eigenvalue problem into standard eigenvalue form. The band structure so obtained agrees with previous calculations, particularly that of Rudge (1969). The calculated Fermi surface distortions are less than 4%, while the density of states and optical masses are 1.50 and 1.47 respectively. The direct interband optical conductivity has also been calculated; its overall magnitude is in reasonable agreement with measurements by Mathewson and Myers (1973). The calculation predicts a sharp absorption edge at 3.4 eV, in agreement with the measurement by Hodgson (1966), and in contrast to the much slower rise in the optical conductivity beginning at 2.4 eV reported by Mathewson and Myers.