Plasma modes of a two-dimensional electron gas with a two-dimensional modulation of the charge density

Abstract
We study the plasma modes of a two-dimensional electron gas in which the equilibrium electron density is a periodic function of both coordinates in the plane of the electron gas. The special case of a square symmetric modulation of the equilibrium density is calculated numerically. The plasmon dispersion displays a band structure similar to that found for single-particle energy bands. The results are compared with those obtained from perturbation theory valid for a weak electron-density modulation.