A More Accurate Generalized Gradient Approximation for Solids

TL;DR

This paper introduces a new nonempirical GGA functional that improves the accuracy of predictions for solids' structural properties over the widely used PBE functional, using a diffuse radial cutoff and gradient expansion.

Contribution

The paper proposes a novel GGA functional based on a diffuse radial cutoff and gradient expansion, maintaining PBE constraints without adjustable parameters.

Findings

Improved lattice constant predictions

Enhanced accuracy for crystal structures

Better estimates of metal surface energies

Abstract

We present a new nonempirical density functional generalized gradient approximation (GGA) that gives significant improvements for lattice constants, crystal structures, and metal surface energies over the most popular Perdew-Burke-Ernzerhof (PBE) GGA. The new functional is based on a diffuse radial cutoff for the exchange-hole in real space, and the analytic gradient expansion of the exchange energy for small gradients. There are no adjustable parameters, the constraining conditions of PBE are maintained, and the functional is easily implemented in existing codes.