Because of the variational character of the most of the modern band structure calculation methods, including LMTO, the calculated electron energies are much more accurate than the wave functions. This affects greatly the optical matrix elements calculations. We investigated the problem of the accurate calculation of the matrix elements in the frameworks of usual band structure methods, basing on the continuity equation for the charge density operator. We have derived an analytical expression for corrections to the common-used formulas for the optical matrix elements. These allow to compute the matrix elements with the same accuracy as the band structure so that the intraband matrix elements are exactly equal to the band electron velocities. A specific prescription is proposed for the optical matrix elements calculation in the frameworks of the LMTO method. The imagine parts of the dielectric functions are calculated for Cu and Pd in the energy range 0.1-20 eV, which agree well with available experimental data.
ASJC Scopus subject areas
- Condensed Matter Physics
- Electronic, Optical and Magnetic Materials