Starting from the Volterra model of dissociated dislocations, a dislocation dissociated into two Shockley partials under the action of the periodic Peierls potential and a general external stress is modeled as a pair of coupled Brownian particles in a washboard potential. It is found that mobility shows a sensitive dependence on the parameters of the interaction between partials. In particular, a resonant-like behavior of the average velocity, for equilibrium separation distances close to half-integer multiples of the period of the Peierls potential, is observed.

PACS numbers: 05.40.--a, 61.72.Lk