In the most simple approach, the photoreactivity of compounds can be studied by performing static calculations of characteristic points on the potential energy surfaces of the electronic states such as potential energy minima or crossing points of different electronic states. In this way, static investigations can often establish heuristic models of photoreactions. Equipped with modern computational resources and efficient quantum chemistry programs, such approaches have become affordable to allow even screening of large libraries of photoactive compounds, albeit somewhat restricted to the usage of low-cost black-box electronic structure methods. Beyond the heuristic models, more insight into the mechanisms of photoreactions can be gained by simulating their dynamics explicitly. Depending on the problem of interest, different techniques exist to simulate the nuclear motion of a molecule on the potential energy surfaces of its electronic states. For small molecules or reactions depending only on a small number of nuclear degrees-of-freedom, highly accurate quantum wave-packet dynamics can be employed , while for larger-sized problems typically mixed-quantum-classical approaches such as nonadiabatic molecular dynamics are employed. Both approaches require a large number of electronic structure calculations to either precompute the potential energy surfaces or evaluate electronic energies, gradients, and couplings "on-the-fly". These requirements become de facto bottlenecks for any attempts at screening photodynamics, and they are more severe for transition-metal complexes which typically need more sophisticated and costly electronic structure methods compared to organic molecules.