Journal of Statistical Physics, Vol. 65, Nos. 3/4, 1991. p. 761-771.
Using a previously derived general formalism for a dissipative quantum particle in a boson bath, we prove that when the damping is Ohmic, the Kubo-Einstein relation between the diffusion constant and the linear mobility D = kTM holds to all orders in V0 for a periodic potential V(x)= V0 cos(k0x).