Abstract
We extend to the case of a finite set of stochastic variables whose distributionP obeys a nonlinear Fokker-Planck equation our previous treatment of diffusion in a bistable potentialU, in the limit of small, constant diffusion coefficient. This is done with the help of an extended WKB approximation due to Gervais and Sakita. The treatment is valid if there exists a well-defined most probable path connecting the minima ofU, and if the valley ofU along that path has a slowly varying width, and weak curvature and twisting. We find that: (i) the final approach to equilibrium is governed by Eyring's generalization of the Kramers high-viscosity rate, which we rederive; (ii) for intermediate times, if the initial distribution is concentrated in the region of instability (close vicinity of the saddle point ofU),P has, along the most probable path, the behavior described by Suzuki's scaling statement for a one-dimensional system. In a second part of this time domain,P enters the diffusive regions around the minima ofU and relaxes toward local longitudinal equilibrium on a time comparable with Suzuki's time scale. The time for relaxation toward transverse local equilibrium may, depending on the initial conditions, compete with these longitudinal times.
Similar content being viewed by others
References
B. Caroli, C. Caroli, and B. Roulet,J. Stat. Phys. 21:415 (1979).
H. A. Kramers,Physica 7:284 (1940).
H. Suzuki,J. Stat. Phys. 16:11 (1977) and references therein.
T. Banks, C. M. Bender, and T. T. Wu,Phys. Rev. D 8:3346 (1973); T. Banks and C. M. Bender,Phys. Rev. D 8:3366 (1973).
J. L. Gervais and B. Sakita,Phys. Rev. D 16:3507 (1977).
S. Glasstone, K. Laidler, and H. Eyring,The Theory of Rate Processes (McGraw-Hill, New York, 1966).
C. D. Graham,Metal Progress 71:75 (1957).
Author information
Authors and Affiliations
Additional information
We dedicate this work to our colleague, Yuri Orlov.
Rights and permissions
About this article
Cite this article
Caroli, B., Caroli, C., Roulet, B. et al. A WKB treatment of diffusion in a multidimensional bistable potential. J Stat Phys 22, 515–536 (1980). https://doi.org/10.1007/BF01011336
Received:
Revised:
Issue Date:
DOI: https://doi.org/10.1007/BF01011336