Modeling of ultrafast electron-transfer processes: Validity of multilevel Redfield theory

The capability of multilevel Redfield theory to describe ultrafast photoinduced electron-transfer reactions is investigated. Adopting a standard model of photoinduced electron transfer in a condensed-phase environment, we consider electron-transfer reactions in the normal and inverted regimes, as well as for different values of the electron-transfer parameters, such as reorganization energy, electronic coupling, and temperature. Based on the comparison with numerically exact reference results, obtained using the self-consistent hybrid method, we discuss in some detail the advantages and shortcomings of two different versions of Redfield theory, which employ the time-dependent and stationary Redfield tensor, respectively. The results of the study demonstrate that multilevel Redfield theory, if applied in the appropriate parameter regime, is well suited to describe the ultrafast coherent dynamics of photoinduced electron-transfer reactions. (C) 2003 American Institute of Physics.