1205.1994 (Davide Sangalli et al.)

Pseudo-potentials based first-principles approach to the magneto-optical
Kerr effect: from metals to the inclusion of local fields and excitonic
effects    [PDF]

Davide Sangalli, Andrea Marini, Alberto Debernardi

We propose a first-principles scheme for the description of the magneto-optical kerr effect within density functional theory (DFT). As a first steps, using as reference materials iron, cobalt and nickel we show that pseudo-potential based calculations give accurate predictions. Though the computation of Kerr parameters is often done within DFT, starting from the conductivity or the dielectric tensor, there is no formal justification to this choice. In this work we derive a formal expression for the full dielectric tensor in terms of the density-density correlation function. The derived equation is exact in systems with an electronic gap and whenever the time reversal symmetry holds and can be used as a starting point for the inclusion of local fields and excitonic effects within time-dependent DFT for such systems. In case of metals instead we show that, starting from the density-density correlation function, the term which describes the anomalous Hall effect is neglected giving a wrong conductivity.

View original: http://arxiv.org/abs/1205.1994