2,790 research outputs found
SCAN+rVV10: A promising van der Waals density functional
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
Energy scaling law for nanostructured materials
The equilibrium binding energy is an important factor in the design of
materials and devices. However, it presents great computational challenges for
materials built up from nanostructures. Here we investigate the binding-energy
scaling law from first-principles calculations. We show that the equilibrium
binding energy per atom between identical nanostructures can scale up or down
with nanostructure size. From the energy scaling law, we predict finite
large-size limits of binding energy per atom. We find that there are two
competing factors in the determination of the binding energy: Nonadditivities
of van der Waals coefficients and center-to-center distance between
nanostructures. To uncode the detail, the nonadditivity of the static multipole
polarizability is investigated. We find that the higher-order multipole
polarizability displays ultra-strong intrinsic nonadditivity, no matter if the
dipole polarizability is additive or not.Comment: 13 pages, 4 figures, 7 table
- …