Singlet fission spin dynamics from molecular structure: A modular computational pipeline.

Singlet fission (SF), which has applications in areas ranging from solar energy to quantum information, relies critically on transitions within a multi-spin manifold. These transitions are driven by fluctuations in the spin-spin exchange interaction, which have been linked to changes in nuclear geometry or exciton migration. While simple calculations have supported this mechanism, to date, limited efforts have been made to model realistic fluctuations, which are informed by the actual structure and properties of physical materials. In this paper, we develop a modular computational pipeline for calculating SF spin dynamics by way of electronic structural calculations, molecular dynamics, and numerical models of spin dynamics. The outputs of this pipeline aid in the interpretation of measured spin dynamics and allow us to place constraints on geometric fluctuations, which are consistent with these observations.