Perturbative spin-orbit couplings for the simulation of extended framework materials.

A comprehensive description of photo-chemical processes in materials, comprising spin-forbidden processes such as intersystem crossing and phosphorescence, implies taking into account spin-orbit coupling. We present an efficient implementation of a perturbative spin-orbit coupling correction for the Tamm-Dancoff approximation of linear-response time-dependent density functional theory within a mixed Gaussian and plane wave framework relying on spin-orbit coupling corrected pseudopotentials. The implementation is validated for a benchmark set of small aromatic molecules, with mean errors in excitation energies and spin-orbit coupling matrix elements being in the range of 0.1-0.6 eV and 1.0-14.4 cm-1, respectively, in comparison with density functional theory and density functional theory multi-reference configuration interaction reference results. Computational timings are given for a bismuth-containing metal-organic framework.