Thomas-Fermi-Dirac-von Weizsacker hydrodynamics in laterally modulated electronic systems

We have studied the collective plasma excitations of a two-dimensional elec tron gas with an arbitrary lateral charge-density modulation. The dynamics is formulated using a previously developed hydrodynamic theory based on the Thomas-Fermi-Dirac-von Weizsacker approximation. In this approach, both th e equilibrium and dynamical properties of the periodically modulated electr on gas are treated ina consistent fashion. We pay particular attention to t he evolution of the collective excitations as the system undergoes the tran sition from the ideal two-dimensional limit to the highly localized one-dim ensional limit. We also calculate the power absorption in the long-waveleng th limit to illustrate the effect of the modulation on the modes probed by far-infrared transmission spectroscopy. [S0163-1829(99)10403-X].