Abstract
The newly developed "strongly constrained and appropriately normed" (SCAN) meta-generalized-gradient approximation (meta-GGA) can generally improve over the non-empirical Perdew-Burke-Ernzerhof (PBE) GGA not only for strong chemical bonding, but also for the intermediate-range van der Waals (vdW) interaction. However, the long-range vdW interaction is still missing. To remedy this, we propose here pairing SCAN with the non-local correlation part from the rVV10 vdW density functional, with only two empirical parameters. The resulting SCAN+rVV10 yields excellent geometric and energetic results not only for molecular systems, but also for solids and layered-structure materials, as well as the adsorption of benzene on coinage metal surfaces. Especially, SCAN+rVV10 outperforms all current methods with comparable computational efficiencies, accurately reproducing the three most fundamental parameters---the inter-layer binding energies, inter-, and intra-layer lattice constants---for 28 layered-structure materials. Hence, we have achieved with SCAN+rVV10 a promising vdW density functional for general geometries, with minimal empiricism.
Highlights
In 2004, graphene, the first two-dimensional (2D) material, was experimentally realized [1], triggering the renaissance of layered materials in both condensed matter physics and materials science
With the large b 1⁄4 15.7 parameter from Ar2 binding curve fitting, SCANþrVV10 approaches the accuracy of the original rVV10 for these molecular systems, better than the van der Waals (vdW)-DF2, which underestimates the interaction energies for S22 by about 15% on average
The comparison between the random-phase approximation (RPA), PBE, strongly constrained and appropriately normed (SCAN), and SCANþrVV10 is given. Both SCANþrVV10 and SCAN are only slightly better than PBE and RPA. For the lattice volume, we found that SCANþrVV10 is essentially as good as RPA, it behaves to SCAN for most solids, and it is much better than the PBE functional that overestimates, with the mean absolute relative error about 3%
Summary
In 2004, graphene, the first two-dimensional (2D) material, was experimentally realized [1], triggering the renaissance of layered materials in both condensed matter physics and materials science. H-BN, transition-metal dichalcogenides, black phosphorus, etc., have demonstrated various new concepts and potential technical applications [12,13,14,15]. Despite much progress, the effort continues to find a vdW density functional with an acceptable accuracy for layered materials [16,17,18,19]. None of the density functionals tested in Refs.
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