Efficient Computation of Nonadiabatic Coupling Coefficients for Modeling Charge Carrier Recombination in Extended Systems: The Case of Metal-Organic Frameworks.

Modeling excited state charge carrier dynamics and recombination in extended systems, such as metal-organic frameworks (MOFs), covalent organic frameworks (COFs), and other hybrid organic-inorganic materials, by surface-hopping approaches is a challenging task due to the high computational cost. In this work, the steps of the simulations and the bottlenecks for such systems are analyzed. In particular, the bottlenecks related to computation of the nonadiabatic coupling coefficients (NACs) are considered. A simple, inexpensive, and portable scheme for computing scalar NACs employing a grid representation of the wave functions is presented and implemented in a Python code. It is tested for the simulation of the electron-hole nonradiative recombination in the MIL-125-NH model system. The proposed approach allows for an on-the-fly estimation of the NACs alongside the simulation of the molecular dynamics trajectory and enables a straightforward interface between the Python libraries for nonadiabatic molecular dynamics and the majority of the existing quantum chemical codes.