Density-functional versus wave-function methods: Toward a benchmark for the jellium surface energy

For the surface energy of jellium at alkali-metal densities, the local-dens ity approximation (LDA) and more advanced density-functional methods disagr ee strongly with the wave-function-based Fermi hypernetted-chain and diffus ion Monte Carlo methods. We present a wave-vector interpolation correction to the generalized gradient approximation which gives jellium surface energ ies consistent with two other estimates based on advanced density functiona ls. LDA makes compensating errors at intermediate and small wave vectors. S tudies of small jellium clusters also support the density-functional estima te for the jellium surface energy.