THE DIFFUSION EQUATION FOR A MECHANICAL SYSTEM IN THE HIGH-FRICTION LIMIT

A configurational diffusion equation for a unidimensional classical mechanical system coupled to a heat reservoir through frictional forces is established. The explicit expressions for the diffusion coefficient and the drift velocity which were formulated in preceding articles are evaluated here by an expansion in inverse powers of the frictional constant up to fifth order. The results are consistent with those obtained in the literature by projection of the full Fokker-Planck equation in phase-space onto configuration space.