COMPUTATIONAL STUDY OF MANY-DIMENSIONAL QUANTUM VIBRATIONAL-ENERGY REDISTRIBUTION .1. STATISTICS OF THE SURVIVAL PROBABILITY

We statistically analyze the dynamics of vibrational energy flow in a model system of anharmonic oscillators which are nonlinearly coupled, with a local topology. The spectra of many basis states of similar ene rgy are computed, for different values of the magnitude of the couplin g in the Hamiltonian between these states. From individual spectra of zero order basis states at each coupling strength the individual survi val probabilities are determined, which are then used in computing sta tistical averages. When the average fluctuation of the survival probab ility is small, in the strongly coupled limit, the average survival pr obability closely follows a semiclassical diffusion prediction and ref lects a predicted linear dependence of the rate of energy flow on coup ling strength. When the average fluctuation is large, in the weakly co upled limit, the average survival probability closely follows a power law decay of t(-1), in agreement with a quantum extension of the diffu sion picture. In this regime, individual survival probabilities show s trong quantum beats. We conclude that these large variations reflect a strong influence of quantum interference in the weakly coupled limit. (C) 1996 American Institute of Physics.