ELECTROMAGNETIC ABSORPTION IN FINITE SYSTEMS AND THE CROSSOVER TO MACROSCOPIC BEHAVIOR

The dynamic conductivity of one-dimensional isolated finite rings is c alculated with emphasis on the low-frequency domain. A quantum-mechani cal linear-response formula is used for both ordered and weakly or str ongly disordered rings. The configurational average of the conductivit y shows a macroscopic behavior of either localized or metallic type, d epending on the size, degree of disorder, and inelastic scattering par ameter gamma. The scaling behavior in the limit omega --> 0, gamma --> 0 (omega/gamma = const) is shown to fit a kinetic description corresp onding to a Drude law for ordered systems and to a hoppinglike picture for the strongly localized ones.