We recently extended electronic dynamics to include relativistic effects, such as spin-orbit coupling. These effects are critical when investigating heavy elements and spin phenomena in chemistry. Using our new method, we showed how you can easily obtain the full absorption spectrum for molecules and atoms that includes otherwise spin-forbidden processes. Non-relativistic theories cannot capture these physical phenomena that show up in experiment. The method, which we call real-time exact two-component theory (RT-X2C), is based on uniting real-time time-dependent density functional theory (RT-TDDFT) with relativistic exact two-component (X2C) Hamiltonians. This allows a fuller, more physical, simulation of experimental systems, especially those containing spin centers and heavy elements. You can read the paper here.
