SCAN: Strongly Constrained & Appropriately Normed Semilocal Density Functional

The ground-state energy, electron density, and related properties of atoms, molecules, condensed matter, and surfaces can be computed efficiently when the exchange-correlation energy as a functional of the density is approximated semilocally. We propose the first meta-generalized gradient approximation that is fully constrained (obeying all 17 exact constraints that a meta-GGA can). It is also exact for “appropriate norms” (not only the slowly-varying electron gas and the H atom, but also rare-gas atoms). This nonempirical SCAN meta-GGA can achieve remarkable accuracy when the exact exchange-correlation hole is localized near its electron, and especially for geometries, weak interactions, heats of formation, defect formation energies, etc. (Supported in part by NSF-DMR 1305135).