Describing van der Waals Interaction in diatomic molecules with generalized gradient approximations: The role of the exchange functional

Zhang, Yingkai; Pan, Wei; Yang, Weitao

doi:10.1063/1.475105

Cited by 297 publications

(233 citation statements)

References 32 publications

(45 reference statements)

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“…In this respect, the case of C 3 H is illustrative with a swap in the energies of linear and cyclic structures between B3LYP and CCSD(T) calculations (see Appendix A below). This level of theory would not be relevant either for the study of weak interactions, like adsorption at the surface of interstellar grains, because of a wrong behavior of the exchange-correlation functional at large atomic separation and the PW91 (or similar functionals) should be preferred in this case (see for example Wesolowski et al 1997;Zhang, et al 1997;Wesolowski 2000).…”

Section: Computational Backgroundmentioning

confidence: 99%

A new weapon for the interstellar complex organic molecule hunt: the minimum energy principle

Lattelais¹,

Pauzat²,

Ellinger³

et al. 2010

A&A

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Context. The hunt for the interstellar complex organic molecules (COMs) supposed to be the building blocks of the molecules at the origin of life is a challenging but very expensive task. It starts with laboratory experiments, associated with theoretical calculations, that give the line frequencies and strengths of the relevant molecules to be identified and finishes with observations at the telescopes. Aims. The present study aims to suggest possible guidelines to optimize this hunt. Levering on the minimum energy principle (MEP) presented in a previous study, we discuss the link between thermodynamic stability and detectability of a number of structures in the important families of amides, sugars and aminonitriles. Methods. The question of the relative stability of these different species is addressed by means of quantum density functional theory simulations. The hybrid B3LYP formalism was used throughout. All 72 molecules part of this survey were treated on an equal footing. Each structure, fully optimized, was verified to be a stationary point by vibrational analysis. Results. A comprehensive screening of 72 isomers of CH 3 NO, C 2 H 5 NO, C 3 H 7 NO, C 2 H 4 O 2 , C 3 H 6 O 3 and C 2 H 4 N 2 chemical formula has been carried out. We found that formamide, acetamide and propanamide (the first two identified in the Inter-Stellar Medium) are the most stable compounds in their families demonstrating at the same time that the peptide bond >N-C=O at the origin of life is the most stable bond that can be formed. Dihydroxyacetone, whose detection awaits for confirmation, is far from being the most stable isomer of its family while aminoacetonitrile, that has been recently identified, is effectively the most stable species. Conclusions. The MEP appears to be a useful tool for optimizing the hunt for new species by identifying the potentially more abundant isomers of a given chemical formula.

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Section: Computational Backgroundmentioning

confidence: 99%

A new weapon for the interstellar complex organic molecule hunt: the minimum energy principle

Lattelais¹,

Pauzat²,

Ellinger³

et al. 2010

A&A

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“…Unlike exchange [11] in PW91 [1], PBE [2], and RPBE [4], E ZY x shows no tendency to bind any of the vdW systems we have tried it on, unless the vdW correlation is actually included in the calculation. We thus take…”

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confidence: 99%

Van der Waals Density Functional for Layered Structures

Rydberg

Dion²,

Jacobson³

et al. 2003

Phys. Rev. Lett.

659

644

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To understand sparse systems we must account for both strong local atom bonds and weak nonlocal van der Waals forces between atoms separated by empty space. A fully nonlocal functional form [H. Rydberg, B.I. Lundqvist, D.C. Langreth, and M. Dion, Phys. Rev. B 62, 6997 (2000)] of density-functional theory (DFT) is applied here to the layered systems graphite, boron nitride, and molybdenum sulfide to compute bond lengths, binding energies, and compressibilities. These key examples show that the DFT with the generalized-gradient approximation does not apply for calculating properties of sparse matter, while use of the fully nonlocal version appears to be one way to proceed.PACS numbers: 71.15. Mb, 61.50.Lt, 31.15.Ew, Calculations of structure and other properties of sparse systems must account for both strong local atom bonds and weak nonlocal van der Waals (vdW) forces between atoms separated by empty space. Present methods are unable to describe the true interactions of sparse systems, abundant among materials and molecules. Key systems, like graphite, BN, and MoS 2 , have layered structures. While today's standard tool, density-functional theory (DFT), has broad application, the common local (LDA) and semilocal density approximations (GGA) [1,2,3,4] for exchange and correlation, E xc [n], fail to describe the interactions at sparse electron densities. Here we show that the recently proposed density functional [5] with nonlocal correlations, E nl c [n], gives separations, binding energies, and compressibilities of these layered systems in fair agreement with experiment. This planar case bears on the development of vdW density functionals for general geometries [6,7], as do asymptotic vdW functionals [8].Figure 1 with its 'inner surfaces' defines the problem: voids of ultra-low density, across which electrodynamics leads to vdW coupling. This coupling depends on the polarization properties of the layers themselves, and not on small regions of density overlap between the layers, excluding proper account in LDA or GGA. For large interplanar separation d the vdW interaction energy between planes behaves as −c 4 /d 4 , while LDA or GGA necessarily predicts an exponential falloff. Layers rolled up to form two (i) nanotubes with parallel axes a distance l apart interact as −c 5 /l 5 , or (ii) balls (e.g., C 60 ), a distance r apart, as −c 6 /r 6 . If by fluke an LDA or GGA were to give the correct equilibrium for one shape, it would necessarily fail for the others. The simple expedient of adding the standard asymptotic vdW energies as corrections to the correlation energy of LDA or GGA also fails. The true vdW interaction between two close sheets must be (i) substantially stronger (Fig. 1), (ii) seamless, and (iii) saturate as d shrinks (Fig. 2).Like earlier work directly calculating nonlocal correlations between two jellium slabs [9], the vdW density functional (vdW-DF) theory [5] used here exploits assumed planar symmetry. It divides the correlation energy functional into two pieces,, where E nl c [n] is defined to in...

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“…These have been shown to be important for transition metals, in contrast to the long range separations generally dominating in van der Waals systems. [43][44][45][46] The order of the functionals in the table follows the gradient of the exchange enhancement factor (F x ) with small reduced density gradients (s), s < 1, included in the models, being steep for GGA and vdW-DF and flat for LDA. 29 Looking at lattice constant b, the length decreases going down the table, suggesting a correlation with F x at small s. The same trend from vdW-DF to LDA can be seen with the a parameter, in which direction the octahedra are cornersharing, giving some flexibility in ionic positions.…”

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confidence: 99%

A van der Waals Density Functional Study of MoO₃ and Its Oxygen Vacancies

et al. 2016

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The electronic structure of layered molybdenum trioxide MoO 3 is highly sensitive to changes in oxygen stoichiometry as Mo 6+ has an empty 4d shell. Applications of MoO 3 are responsive to small changes in vacancy concentration, with some functions relying on a narrow window of oxygen non-stoichiometry. Difficulties in analyzing the energetics of oxygen vacancies by computational methods stem from the inability to accurately model the layered structure of MoO 3 . One unit cell parameter is governed by long range forces across the structural gaps and these dispersed interactions are not well described by conventional density functional theory (DFT) methods. With the exchange functional vdW-DF2 we accurately model the structure, in good agreement with experimental data. This basis allows exploration of the effect of oxygen non-stoichiometry on the electronic structure and properties of the oxygen deficient material.The layered structure efficiently screens the structural perturbations caused by oxygen vacancies.The enthalpies of formation are calculated for oxygen vacancies at the three symmetry inequivalent oxygen sites. The oxygen deficiency in MoO 3 gives rise to Mo 4d gap states with energy levels dependent on the type of oxygen vacancy.

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Describing van der Waals Interaction in diatomic molecules with generalized gradient approximations: The role of the exchange functional

Cited by 297 publications

References 32 publications

A new weapon for the interstellar complex organic molecule hunt: the minimum energy principle

A new weapon for the interstellar complex organic molecule hunt: the minimum energy principle

Van der Waals Density Functional for Layered Structures

A van der Waals Density Functional Study of MoO₃ and Its Oxygen Vacancies

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Describing van der Waals Interaction in diatomic molecules with generalized gradient approximations: The role of the exchange functional

Cited by 297 publications

References 32 publications

A new weapon for the interstellar complex organic molecule hunt: the minimum energy principle

A new weapon for the interstellar complex organic molecule hunt: the minimum energy principle

Van der Waals Density Functional for Layered Structures

A van der Waals Density Functional Study of MoO3 and Its Oxygen Vacancies

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Product

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A van der Waals Density Functional Study of MoO₃ and Its Oxygen Vacancies