Rapid calculation of internal conversion and intersystem crossing rate for organic materials discovery

The internal conversion (IC) process from S-1 to S-0 and the intersystem crossing (ISC) transition from T-1 to S-0 are two essential processes in functional molecular material design. Despite their importance, it is currently impossible to evaluate the rate of these processes for a large set of molecules and, therefore, perform high-throughput virtual screening in large-scale data to gain more physical insight. In this work, we explore possible approaches to accelerate the calculations of IC and ISC rates based on a systematic reduction of the number of modes included in the computation and the study of the importance of the different parameters and the influence of their accuracy on the final result. The results reproduce the experimental trends with systematic errors that are ultimately due to the approximations of the theory. We noted that plausible results for ISC in planar molecules are only obtained by including the effect of Hertzberg-Teller coupling. Our method establishes the feasibility and expected accuracy of the computation of nonradiative rates in the virtual screening of molecular materials. (C) 2022 Author(s).

Automated summary

This study explores methods to accelerate the calculation of rates for internal conversion and intersystem crossing processes in molecules. By reducing the number of modes included in the computation and studying the importance of different parameters and their accuracy, the results reproduce experimental trends and establish the feasibility and expected accuracy of computing nonradiative rates in the virtual screening of molecular materials.