Strongly Constrained and Appropriately Normed Semilocal Density Functional

TL;DR

The paper introduces SCAN, a fully constrained meta-GGA density functional that achieves high accuracy for various systems by obeying all known exact constraints and fitting key norms.

Contribution

It presents the first meta-GGA functional that is fully constrained and normed, improving the accuracy of density functional calculations.

Findings

Achieves high accuracy for lattice constants and weak interactions.

Obeys all 17 known exact constraints for meta-GGAs.

Performs well for systems with localized exchange-correlation holes.

Abstract

The ground-state energy, electron density, and related properties of ordinary matter can be computed efficiently when the exchange-correlation energy as a functional of the density is approximated semilocally. We propose the first meta-GGA (meta-generalized gradient approximation) that is fully constrained, obeying all 17 known exact constraints that a meta-GGA can. It is also exact or nearly exact for a set of appropriate norms, including rare-gas atoms and nonbonded interactions. This SCAN (strongly constrained and appropriately normed) meta-GGA achieves remarkable accuracy for systems where the exact exchange-correlation hole is localized near its electron, and especially for lattice constants and weak interactions.