Excitation of a quantum gas of independent particles under periodic perturbation in integrable or nonintegrable potentials

The excitation of a quantum gas of 112 independent fermions in the time-dependent potential well, periodically oscillating around the spherical shape, was followed over ten oscillation cycles. Five different oscillation frequencies are considered for each of the five types of deformations: spheroidal and Legendre polynomial ripples P{sub 3}, P{sub 4}, P{sub 5}, and P{sub 6}. The excitation rate of the gas in the deforming hard-walled cavities substantially decreases after initial one or two cycles and the final excitation energy is a few times smaller than the wall formula predictions. Qualitatively similar results are obtained for the diffused Woods-Saxon well. The details and possible origins of this behavior are discussed as well as the consequences for the one-body dissipation model of nuclear dynamics. {copyright} {ital 1997} {ital The American Physical Society}