Onsager-Machlup action-based path sampling and its combination with replica exchange for diffusive and multiple pathways.
For sampling multiple pathways in a rugged energy landscape, we propose a novel action-based path sampling method using the Onsager-Machlup action functional. Inspired by the Fourier-path integral simulation of a quantum mechanical system, a path in Cartesian space is transformed into that in Fourier space, and an overdamped Langevin equation is derived for the Fourier components to achieve a canonical ensemble of the path at a finite temperature. To avoid "path trapping" around an initially guessed path, the path sampling method is further combined with a powerful sampling technique, the replica exchange method. The principle and algorithm of our method is numerically demonstrated for a model two-dimensional system with a bifurcated potential landscape. The results are compared with those of conventional transition path sampling and the equilibrium theory, and the error due to path discretization is also discussed.
Fujisaki
Hiroshi
H
Department of Physics, Nippon Medical School, 2-297-2 Kosugi-cho, Nakahara, Kawasaki 211-0063, Japan. fujisaki@nms.ac.jp
Shiga
Motoyuki
M
Kidera
Akinori
A
D000465:Algorithms; D004058:Diffusion; D008956:Models, Chemical; D008958:Models, Molecular; D008968:Molecular Conformation; D013816:Thermodynamics