We derive analytical formulas for the dispersion and damping of acoustic plasmons (i.e., plasmons with linear dispersion at small wave vectors) in a two-dimensional, two-component electron liquid. Our formulas include the effect of short-range correlations by means of local-field corrections, and reduce to the random-phase approximation when these corrections are neglected. Explicit calculations, using a Hubbard-like approximation for the local-field corrections, show that the acoustic plasmon exists only at comparatively small wave vectors. Strong short-range correlations may even suppress it.

• Received 19 October 1987

DOI:https://doi.org/10.1103/PhysRevB.38.811