Green’s-function quantum Monte Carlo study of a jellium surface

A jellium slab at the average valence-charge density of aluminum (${\mathit{r}}_{\mathit{s}}$=2.07) is studied with use of a Green’s-function quantum Monte Carlo (GFMC) technique in the fixed-node and diffusion approximations. The trial function is of Slater-Jastrow type, with a pair-correlation term accounting for the anisotropy arising from the surfaces. The GFMC electron density is very similar to that obtained from local-density-approximation (LDA) calculations. The GFMC surface energy is slightly higher than the LDA result and is very close to the value obtained from calculations using the Langreth-Mehl nonlocal-density functional, but significantly lower than predicted by Fermi-hypernetted-chain calculations.