EFFECTS OF 3-BODY AND BACKFLOW CORRELATIONS IN THE 2-DIMENSIONAL ELECTRON-GAS

We investigate the effects of three-body and backflow correlations on ground-state properties of the two-dimensional electron gas by both variational and fixed-node Green's-function Monte Carlo methods. It is found that the backflow effect is dominant over the three-body effect at high density (r(s) approximately 1) while they are of equal importance at the lowest density considered (r(s) approximately 20). With these correlations, we find significant improvements in both variational and fixed-node energies over the Slater-Jastrow results which consider only two-body correlation. The effects are comparable to those in bulk He-3. We present an analytic expression for the correlation energy of the two-dimensional electron gas as a function of the density.