Simulation of electron and nuclear spin dynamics in many-spin charge-separated states

We have presented a MATLAB-based implementation of the numerical simulation approach for calculating the magnetic field effects on any spin-dependent observable in a radical pair with a fixed exchange interaction and multiple hyperfine interactions between electron and magnetic nuclear spins. In particular, we validate this through the calculation of both the CIDNP and MARY field dependences for donor-bridge-acceptor dyads D-X-A and D-Ir-A. The main features of this approach are as follows: firstly, it has the capacity to accommodate systems comprising numerous nuclei through the utilization of a semiclassical description of hyperfine interactions; secondly, it incorporates an automated optimization of model parameters during the process of identifying the most accurate fit to experimental  data.  Utilizing this approach allows the extraction of valuable information about short-lived radical pairs, including the sign and magnitude of the exchange interaction, the distribution of electron spin density within the radical, and the parameters related to the mobility of the bound radical pair. The number of parameters that can be extracted in practice is determined by the quantity and quality of the experimental data available for simulation.