FIELD-INDUCED LOCALIZATION AND NONLINEAR RESPONSE OF A ONE-BAND CONDUCTOR TO A PERIODIC ELECTRIC-FIELD

The nonlinear nonstationary response of a crystalline conductor to an external space-homogeneous electric field of arbitrary magnitude and a rbitrary time dependence is considered. The independent-electron one-b and approach in arbitrary dimension with dispersion and lattice struct ure of general type and no relaxation is used. A classification of osc illatory localized states, induced by time-periodic electric fields is studied. The governing parameters are the magnitude of the constant c omponent of the field and the period of its oscillating part. In the P eriodic regime the electron is typically delocalized with the exceptio n of dynamic localization. In the Commensurate case the electron is de localized only due to long-range transfer to distant neighbours with t he analogous localized exception. And, last, in the Incommensurate reg ime the electron is always localized. Particular examples, illustratin g all the localization regimes, are considered. The characteristic fea tures (plateaus and peaks) in the generated harmonics' spectrum are st udied. (C) 1998 Elsevier Science B.V. All rights reserved.