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 (Perdew J P et al 1996 Phys. Rev. Lett. 77 3865), for example, as implemented in the HSE design (Heyd J et al 2003 J. Chem. Phys. 118 8207). Here we define an analytical-hole (Henderson T M et al 2008 J. Chem. Phys. 128 194105) consistent-exchange RSH extension to the van der Waals density functional (vdW-DF) method (Berland K et al 2015 Rep. Prog. Phys. 78 066501), launching vdW-DF-ahcx. We characterize the GGA-type exchange in the vdW-DF-cx version (Berland K and Hyldgaard P 2014 Phys. Rev. B 89 035412), 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.

Hard and soft materials: putting consistent van der Waals density functionals to work

“…revPBE + D3 is a generalist that also does well for the here-considered biomolecular subset of the full GMTKN55 molecular testing suite [87]. The CX has a similar generalist status [15,25], and table 4 shows that CX matches the revPBE + D3 performance also in this more targeted survey. Moreover, we find that the hybrid forms, CX0P and AHCX, improve the accuracy for biomolecular problems, as asserted in this test.…”

“…Figure 7 shows a performance comparison for the CX-based consistent-vdW-DF tool chain, CX, CX0P, and AHCX. The performance of the consistent-vdW-DFs (CX/CX0P/AHCX) is strong overall on molecules [15] and very strong for most of the here-investigated bio-relevant problems. The performance is clearly better than, for example, that of the vdW-DF1 version [17].…”

“…The latter tool chain is defined by consistent vdW-DFs [25] and is new. It comprises CX [4,26], CX0P [14], and AHCX [15].…”

“…It resembles the CX0P in that we keep the Fock exchange fraction fixed at 20% and it resembles HSE in that we keep the screening parameter fixed at the standard HSE value [12]. The screening makes AHCX calculations relevant for metallic systems [15].…”

Accurate non-empirical range-separated hybrid van der Waals density functional for complex molecular problems, solids, and surfaces

“…Nonlocal-correlation functionals of the van der Waals (vdW) density functional (vdW-DF) method fulfill a necessary condition for serving as a general-purpose DFT: They incorporate the ubiquitous van der Waals (vdW) interactions that dominate intermolecular interactions. The vdW-DF method 9,[27][28][29][30][31][32][33][34][35][36][37][38][39][40][41][42][43] is a systematic way to de-sign a truly nonlocal-correlation functional from the insight that we have already gained in making semilocal functionals within the generalized gradient approximation (GGA). 9,[31][32][33][34][43][44][45][46][47][48][49][50][51][52][53] The two first method releases, termed vdW-DF1 (or vdW-DF) and vdW-DF2, have the same overall structure but differ in how a plasmon-response model sets the details of the nonlocalcorrelation energy E nl c and in choice of the exchange component.…”