Johannes Ehrmaier: Pysurf: Database accelerated surface hopping

Light-initiated processes, which lie at the heart of life itself, are critically important in novel technologies, e.g. molecular electronics, optogenetics, or renewable energy devices. Primary photo-induced processes occurring in nature and technology, in general, involve inherently quantum processes such as, electron-hole migration, and proton-coupled electron transfer, which need to be treated in a fully quantum mechanical manner. However, an accurate description of these processes in (supra)molecular systems is still a demanding task due to: (i) the need of high-level electronic structure calculations; (ii) coupled electron-nuclear dynamics; (iii) the large system size. In recent years, trajectory surface hopping (SH) has become popular to study those nonadiabatic processes. In SH the quantum nature of the nuclei and transition between electronic states are taken into account in a purely stochastic fashion. Due to its computational efficient formulation and simplicity, it can also be applied to intermediate to large-sized systems, but still suffers from the huge amount of electronic structure calculations that need to be performed during the simulation.

In this work, we present an innovative solution, based on Landau-Zener surface hopping combined with a database. The amount of electronic structure computations, which are responsible for the high computational costs of the simulations, is drastically reduced. During the dynamics, computations are only carried out for conformational regions that were not visited before. For the already isited parts an interpolation scheme is used to avoid the expensive recomputation at ab-initio level of theory.