Dipole matrix element approach versus Peierls approximation for optical conductivity

Abstract

We develop a computational approach for calculating the optical conductivity in the augmented plane-wave basis set of wien2k and apply it for thoroughly comparing the full dipole matrix element calculation and the Peierls approximation. The results for SrVO${}_{3}$ and V${}_{2}$O${}_{3}$ show that the Peierls approximation, which is commonly used in model calculations, works well for optical transitions between the $d$ orbitals. In a typical transition-metal oxide, these transitions are solely responsible for the optical conductivity at low frequencies. The Peierls approximation does not work, on the other hand, for optical transitions between $p$ and $d$ orbitals which usually became important at frequencies of a few eVs.