A perturbation treatment of oscillating magnetic fields in the radical pair mechanism using the Liouville equation

Abstract This paper describes an application of time-dependent perturbation theory to the calculation of singlet-to-triplet yields in radical pair reactions for oscillating magnetic fields. It outlines an iterative approach, based on the Liouville equation, that holds for any order of perturbation theory. It then compares this method to other methods, namely, numerical integration and the rotating frame treatment as well as methods based on the Schrodinger equation, and gives sample results.