Theoretical studies of energy transfer in disordered condensed media

In this paper we consider energy transfer among impurity molecules in disordered systems. We use the result of Gochanour, Andersen, and Fayer [J. Chem. Phys. 70, 4254 (1979)] for the generalized diffusion coefficient D(t) in terms of the decay function Φ(t), in conjunction with separate calculations of Φ(t) in the pair approximation to compute D(t). Both multipolar and exchange interactions and both short and long time limits are considered. Comparisons to earlier work are made.