Calculation of optical properties with spin-orbit coupling for warm dense matter

Optical properties of warm dense matter are computed within linear response theory using the Kubo-Greenwood formula in the framework of Density Functional Theory and the Projector Augmented-Wave (PAW) method. For transition metals, the effect of spin-orbit coupling (SOC) has to be taken into account. We present the theoretical framework to introduce SOC in the PAW formalism and then to compute optical properties including SOC using the Kubo-Greenwood formula. This formulation has been implemented in the ABINIT software. Moreover, for high energy absorption spectra, we use Dirac relativistic core wave functions from the ATOMPAW code to obtain the correct SOC energy splitting. This implementation enables a description of optical properties for warm dense metals including SOC for both core and valence orbitals. Example calculations are presented for warm dense gold and copper. (C) 2021 Elsevier B.V. All rights reserved.