Low barrier kinetics: dependence on observables and free energy surface.
Dynamics on free energy surfaces with high activation barriers are usually treated by few-state kinetics models, yielding characteristic rate coefficients and amplitudes depending on the connectivity of the states. When the barriers are low (< 3 kT), the assumption of instantaneous equilibration of the transition state, and hence, the few-state kinetics treatment, break down. Langevin dynamics is used here to explore the characteristic trends that occur in such cases, as a function of barrier height, number of barriers, dimensionality of the free energy surface, and switching functions that describe how spectroscopic probes vary from reactant to product. The result is a systematic phenomenological description of low barrier kinetics and dynamics.
Ma
Hairong
H
Center for Biophysics and Computational Biology, A220 CLS Box 5-6, 600 South Matthews Ave., University of Illinois, Urbana, Illinois 61801, USA.
Gruebele
Martin
M
D003198:Computer Simulation; D007700:Kinetics; D008956:Models, Chemical; D013499:Surface Properties; D013816:Thermodynamics