Regularized Gradient Expansion for Atoms, Molecules, and Solids

A new, regularized gradient expansion (RGE) approximation density functional (i.e., a generalized gradient approximation or GGA that recovers the second-order gradient expansion for exchange in the slowly varying limit) was designed in an attempt to obtain good solid-state and molecular properties at the same time from a single GGA. We assess the performance of this functional for molecular atomization energies, solid lattice constants, and jellium surface energies. We compare the performance of this functional to the modified Perdew-Burke-Ernzerhof generalized gradient approximation (PBEsol GGA), the original PBE GGA, and the Tao-Perdew-Staroverov-Scuseria (TPSS) meta-GGA.