vdW-DF-ahcx: a range-separated van der Waals density functional hybrid

Abstract

Hybrid density functionals replace a fraction of an underlying generalized-gradient approximation (GGA) exchange description with a Fock-exchange component. Range-separated hybrids (RSHs) also effectively screen the Fock-exchange component and thus open the door for characterizations of metals and adsorption at metal surfaces. The RSHs are traditionally based on a robust GGA, such as PBE [PRL 77, 3865 (1996)], for example, as implemented in the HSE design [JCP 118, 8207 (2003)]. Here we define an analytical-hole (AH) [JCP 128, 194105 (2008)] consistent-exchange (AHCX) RSH extension to the van der Waals density functional (vdW-DF) method [ROPP 78, 066501 (2015)], launching vdW-DF-ahcx. We characterize the GGA-type exchange in the vdW-DF-cx version [PRB 89, 035412 (2014)], isolate the short-ranged exchange component, and define the new vdW-DF hybrid. We find that the performance vdW-DF-ahcx compares favorably to (dispersion-corrected) HSE for descriptions of bulk (broad molecular) properties. We also find that it provides accurate descriptions of noble-metal surface properties, including CO adsorption.