Temperature dependence of the optical response: Application to bulk GaAs using first-principles molecular dynamics simulations

We present an approach that takes into account lattice dynamical effects in calculating the optical response of semiconductors by averaging over several perturbed configurations of a supercell extracted from molecular dynamic simulations. The validity of this approach is confirmed by comparing our results for the dielectric function of bulk GaAs in the range of 0 - 700 K with our and other highly accurate ellipsometry measurements. The results of our approach resolve the serious discrepancy in energy and line shape between the latest optical models, all of which neglect lattice dynamics, and experiment.