DAMPING AND PUMPING OF LOCALIZED INTRINSIC MODES IN NONLINEAR DYNAMICAL LATTICES

It has been recently demonstrated that dynamical models of nonlinear l attices admit approximate solutions in the form of self-supported intr insic modes (IM's). In this work, the intensity of the emission of rad iation (''phonons'') from the one-dimensional IM is calculated in an a nalytical approximation for the case of a moderately strong anharmonic ity. Contrary to the emission in nonintegrable continuum models, which may be summarized as fusion of several vibrons into a phonon, the emi ssion in the lattice may be described in terms of fission of a vibron into several phonons: as the IM's internal frequency hes above the pho non band of the lattice, the radiative decay of the IM in the discrete system can be only subharmonic. It is demonstrated that the correspon ding lifetime of the IM may be very large. Then, the threshold (minimu m) value of the amplitude of an external ac field, necessary to suppor t the IM in a lattice with dissipative losses, is found for the limiti ng cases of the weak and strong anharmonicity.