Dissipating the Langevin equation in the presence of an external stochastic potential

In the Langevin formalism, the delicate balance maintained between the fluctuations in the system and their corresponding dissipation may be upset by the presence of a secondary, space-dependent stochastic force, particularly in the low-friction regime. In prior. work, the latter was dissipated self-consistently through an additional uniform (mean-field) friction [T. Shepherd and R. Hernandez, J. Chem. Phys. 115, 2430 (2001).] An alternative approach to ensure that equipartition is satisfied relies on the use of a space-dependent friction while ignoring nonlocal correlations. The. approach is evaluated With respect to its ability to maintain constant temperature for two simple one-dimensional, stochastic potentials of mean force wherein the friction can be evaluated explicitly when there is no memory in the barriers. The use of a space-dependent. friction is capable of providing qualitatively similar results to those obtained previously, but in extreme cases deviations from equiparition may be observed due to the neglect of the memory effects present in the stochastic potentials. (c) 2005 American Institute of Physics.