Screened van der Waals correction to density functional theory for solids

The Perdew-Burke-Ernzerhof (PBE) generalized gradient approximation to the exchange-correlation energy is widely used in materials science. For many solids it somewhat overestimates lattice constants and underestimates cohesive energies. What attraction among the ions is missing in PBE? For ionic solids and heavy metals, a detailed analysis shows that the answer is the van der Waals (vdW) interaction arising from electric charge fluctuations on different ions. Our vdW correction to PBE is a short-range damped and long-range screened pairwise interaction among the ions. We find that the three-body interactions are small due to screening, and that the vdW correction stabilizes the bcc structure of cesium halides over the rocksalt structure.