Abstract

Many dynamical problems in solid-state physics and chemistry are related to random-walks on periodic structures. In the last years processes of energy transfer and decay in disordered media have attracted considerable attention. One way to account for the disorder is the continuous-time random walk (CTRW), as used for electron migration in amorphous solids^[1]. The standard CTRW involves a spatial regularization, in that the walk takes place on a periodic lattice and the disorder is mirrored in waiting-time distributions ψ (t)^[2,3]. Another way to mimic the disorder consists in letting the walk take place on fractals, geometrical structures which are not translationally invariant but which display the dilatational symmetry of the percolative cluster^[4,5]. For fixed waiting-times this procedure is complementary to the CTRW, in that the disorder is included in the spatial aspect.

© 1984 Optical Society of America