FLUT: a Numerical Code for Simulations of Multistage Photoinduced Electron Transfer Reactions in Viscous Solutions

摘要

A numerical code for simulations of ultrafast charge separation/charge recombination (CS/CR) kinetics in photoreactions assisted by diffusion of the reactant molecules in viscous media is presented. The FLUT software package is based on the unified theory of CS/CR and employs the well-known concepts of the distance-dependent rate of electron transfer, the probability of hot electronic transition in the course of solvent and intramolecular relaxation, the diffusive escape of reactants from the solvent cage, spin evolution of radical-ion pairs, etc. The package is constructed as a hierarchy of C++ classes representing basic entities of the model. Several specific types of electronic couplings are implemented as the derived classes. The numerical method utilizes the Chebyshev time propagation algorithm with a spatial finite-differencing operator obeying the detailed balance condition. Validation of the code was performed using several benchmark tests; an agreement with exact analytic solutions in the limiting cases is obtained. The parallel version of the code is implemented with the OpenMP interface. The results of the CS/CR simulations in typical donor-acceptor systems are discussed.