VIBRATIONAL-RELAXATION OF CLUSTERS - RELATION TO POTENTIAL SURFACE-TOPOGRAPHY

Simulations by isothermal and isoergic molecular dynamics show that vi brationally-cold clusters, initially at some high-energy point on thei r potential surfaces, relax monotonically down to low-lying minima whe re they are trapped. The most significant point regarding this relaxat ion is that species with sawtoothlike and staircaselike potentials sho w the same qualitative behavior, equilibrating their vibrations after each major saddle crossing. This result justifies the use of transitio n state kinetics for constructing coarse-grained master equations to d escribe the well-to-well flow of population distributions on complex p otential energy surfaces, even in cases such as (KCl)(32) and some pro tein models which have staircase topographies in which large drops in potential energy from one well to the next might suggest nonthermal ki netics could occur. (C) 1997 American Institute of Physics.