title: Dynamical structure functions, collective modes, and energy gap in charged-particle bilayers.
abstract: The dynamical properties of strongly coupled charged-particle bilayers are investigated by molecular dynamics (MD) simulation and theoretical analysis. The spectra of the current correlation functions show the existence of two (in-phase and out-of-phase) longitudinal and two (in-phase and out-of-phase) transverse collective modes. The out-of-phase modes possess finite frequencies at wave numbers k-->0, confirming the existence of the predicted long-wavelength energy gap in the bilayer system. A theoretical model based on an extended Feynman ansatz for the dynamical structure functions provides predictions on the strength of the collective modes that are verified by the MD experiment.
authors.affiliation: Research Institute for Solid State Physics and Optics of the Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest, Hungary.
authors.forename: Z
authors.initials: Z
authors.lastname: Donkó
authors.forename: G J
authors.initials: GJ
authors.lastname: Kalman
authors.forename: P
authors.initials: P
authors.lastname: Hartmann
authors.forename: K I
authors.initials: KI
authors.lastname: Golden
authors.forename: K
authors.initials: K
authors.lastname: Kutasi