Effect of Level Broadening on the Polarizability in a Two-Dimensional System

Abstract

The Lindhard polarizability is calculated in a two-dimensional system in the self-consistent Born approximation by assuming short-range scatterers. The known singularity at q=2k_F, where k_F is the Fermi wave vector, is shown to be rounded off in the presence of impurities. The effect is similar to that of nonzero temperatures in contrast to the result of Nkoma [J. Phys. C 14 (1981) 1685].