Field-induced barrier crossing in a multiwell system

Abstract
The problem of a particle trapped in a sinusoidal potential well in the presence of a monochromatic external field is studied. The critical amplitudes of external field at which the particle can be driven out of the well are calculated. Predictions based on renormalization-group techniques using the pendulum approximation are found to deviate from the results of numerical experiment. Good agreement is obtained by studying the overlap of resonance zones obtained from full nonlinear one-resonance-approximation Hamiltonians. Even though no external noise is present, the particle once driven from a well exhibits a random walk between wells.