Exact solutions for the motion of a particle in a medium with site diagonal and nearest-neighbor off-diagonal dynamic disorder are presented for the first time. Results obtained for the diffusion constant are of relevance to different areas of current interest, such as charge or exciton motion in molecular solids, and motion of light adsorbates on substrates with weak surface potentials.

• Received 29 August 1977

DOI:https://doi.org/10.1103/PhysRevLett.39.1424