Nonmonotonic behavior of mobility in a multidimensional overdamped periodic system

The mobility motion of an overdamped particle subjected to a thermal white noise in a multidimensional coupled periodic potential tilted by a constant force is studied. An approximate expression for the mean velocity of the p article is obtained on the assumption that nontransport variables play the roles of parameters, and the theoretical prediction is compared with a Lang evin simulation. It is observed that the two-dimensional mean velocity can be a nonmonotonic function of the temperature when the curvature of the pot ential at the barriers is less than that at local minima. Moreover, the pea k of mean velocity drifts toward low temperatures and becomes sharper if a third degree of freedom is introduced.