Solid-State Testing of a Van-Der-Waals-Corrected Exchange-Correlation Functional Based on the Semiclassical Atom Theory

Terentjevs, Aleksandrs; Cortona, Pietro; Constantin, Lucian A.; Pitarke, J. M.; Sala, Fabio Della; Fabiano, Eduardo

doi:10.3390/computation6010007

Cited by 19 publications

(24 citation statements)

References 92 publications

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“…Because of its flexibility, VV10 (or rVV10) has seen many adaptions both to different semi-local XC functionals and to different benchmark sets. 59,[61][62][63][64] The vdW-DF flexibility is more limited than that of VV10 both because of the constraints inherit to the method and the fact that the exchange functional must still be a good match with the semi-local correlation description of vdW-DF, which gives a strong preference for "soft" exchange functionals. 40,51 In our new formulation we optimized the parameters of the proposed h new (y) not only to improve the C 6 coefficients but also to improve the binding energies of the S22 set of molecular dimers.…”

Section: Discussionmentioning

confidence: 99%

van der Waals density functional with corrected C6 coefficients

2019

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The non-local van der Waals density functional (vdW-DF) has had tremendous success since its inception in 2004 due to its constraint-based formalism that is rigorously derived from a many-body starting point. However, while vdW-DF can describe binding energies and structures for van der Waals complexes and mixed systems with good accuracy, one long-standing criticism-also since its inception-has been that the C6 coefficients that derive from the vdW-DF framework are largely inaccurate and can be wrong by more than a factor of two. It has long been thought that this failure to describe the C6 coefficients is a conceptual flaw of the underlying plasmon framework used to derive vdW-DF. We prove here that this is not the case and that accurate C6 coefficient can be obtained without sacrificing the accuracy at binding separations from a modified framework that is fully consistent with the constraints and design philosophy of the original vdW-DF formulation. Our design exploits a degree of freedom in the plasmon-dispersion model ωq, modifying the strength of the long-range van der Waals interaction and the cross-over from long to short separations, with additional parameters tuned to reference systems. Testing the new formulation for a range of different systems, we not only confirm the greatly improved description of C6 coefficients, but we also find excellent performance for molecular dimers and other systems. The importance of this development is not necessarily that particular aspects such as C6 coefficients or binding energies are improved, but rather that our finding opens the door for further conceptual developments of an entirely unexplored direction within the exact same constrained-based non-local framework that made vdW-DF so successful in the first place.

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Section: Discussionmentioning

confidence: 99%

van der Waals density functional with corrected C6 coefficients

2019

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“…Both VV10 and rVV10 have two adjustable parameters b and c assuring the compatibility between the semilocal XC functional and E nl c [n]. Recently, several variations of these vdW functionals have been proposed: AM05-VV10sol [40], SCAN+rVV10 [41], PBE+rVV10L [42], SG4+rVV10m [43], C09-vdW-DF [44], vdW-DF-cx [45][46][47][48], PBEsol+rVV10s [49], and rev-vdW-DF2 [50,51]. All these variations have been tested for many vdW systems, such as layered materials [33,[39][40][41][42]45,49,[51][52][53][54][55][56][57][58][59][60][61][62], rare-gas (RG) solids [43,49,62,63], and molecular solids [43,62].…”

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

“…In this paper, we use the recently developed dispersion-corrected XC functionals SG4+rVV10m [43] and PBEsol+rVV10 [49] in the framework of the SIESTA method [91]. These functionals were already realized in the plane-wave based Quantum-Espresso (QE) code [92], combining SG4 and PBEsol semilocal functionals with vdW rVV10 kernels [43,49]. In the case of SIESTA, we combine SG4 and PBEsol with VV10 (instead of rVV10), keeping the same dispersion parameters b and c. The SIESTA method, which uses localized numerical atomic orbitals (NAOs), has a number of advantages with respect to a plane-wave basis set: SIESTA is typically more efficient, as the number of required basis functions is usually smaller, and SIESTA's localized basis set gives a better description of systems where the orbitals are strictly localized in real space, as in the case of adsorption of atoms/molecules on surfaces and in the case of interfaces with different materials.…”

Section: Introductionmentioning

confidence: 99%

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Comparison of dispersion-corrected exchange-correlation functionals using atomic orbitals

et al. 2019

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for the adsorption of a noble-gas atom/monolayer as well as a graphene on the Cu(111), Pt(111), Pd(111), and Ag(111) close-packed surfaces. Most of these systems are characterized by weak interactions between the surface and the atom/monolayer, where the van der Waals interaction dominates. Here we investigate the above mentioned dispersion-corrected exchange-correlation functionals using atomic orbitals instead of plane waves applied in earlier works. We find that PBEsol+VV10s is an optimal functional for such hybrid interfaces, being accurate for both the equilibrium distance and the adsorption energy and providing realistic potential-energy curves. Moreover, we also show that PBEsol+VV10s and SG4+VV10m are both very accurate for the investigation of surface formation energies of all transition metals under consideration.

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“…Non-local density functionals like DFT-DF and DFT-DF2 methods sit in the 3rd rung [3], of which the overall accuracy increases, as well as the computational demand. Recently, a few improvements in vdW-DF methods have been proposed, including optPBE-vdW, optB88-vdW, optB86b-vdW [17,18], vdW-DF2-C09 [19], vdW-DF-cx [20], rev-vdW-DF2 [21], PBE+rVV10 [22], PBEsol+rVV10 [23], SCAN+rVV10 [24], and SG4+rVV10 [25]. These methods are designed to minimize the error of the binding energies and interaction energy curves in a certain collection of materials, such as the S22 data set [26], aiming for a general use for all materials.…”

Section: Introductionmentioning

confidence: 99%

Van der Waals Density Functional Theory vdW-DFq for Semihard Materials

et al. 2019

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There are a large number of materials with mild stiffness, which are not as soft as tissues and not as strong as metals. These semihard materials include energetic materials, molecular crystals, layered materials, and van der Waals crystals. The integrity and mechanical stability are mainly determined by the interactions between instantaneously induced dipoles, the so called London dispersion force or van der Waals force. It is challenging to accurately model the structural and mechanical properties of these semihard materials in the frame of density functional theory where the non-local correlation functionals are not well known. Here, we propose a van der Waals density functional named vdW-DFq to accurately model the density and geometry of semihard materials. Using β -cyclotetramethylene tetranitramine as a prototype, we adjust the enhancement factor of the exchange energy functional with generalized gradient approximations. We find this method to be simple and robust over a wide tuning range when calibrating the functional on-demand with experimental data. With a calibrated value q = 1.05 , the proposed vdW-DFq method shows good performance in predicting the geometries of 11 common energetic material molecular crystals and three typical layered van der Waals crystals. This success could be attributed to the similar electronic charge density gradients, suggesting a wide use in modeling semihard materials. This method could be useful in developing non-empirical density functional theories for semihard and soft materials.

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Solid-State Testing of a Van-Der-Waals-Corrected Exchange-Correlation Functional Based on the Semiclassical Atom Theory

Cited by 19 publications

References 92 publications

van der Waals density functional with corrected C6 coefficients

van der Waals density functional with corrected C6 coefficients

Comparison of dispersion-corrected exchange-correlation functionals using atomic orbitals

Van der Waals Density Functional Theory vdW-DFq for Semihard Materials

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