The noble gas dimers as a probe of the energetic contributions of dispersion and short-range electron correlation in weakly bound systems

Housden, Michael P.; Pyper, N.C.

doi:10.1080/00268970701618432

Cited by 9 publications

(5 citation statements)

References 47 publications

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“…͑2.1͒ yields the interaction of species G and H separated by a distance r GH after subtracting any point Coulombic energy equal to the product of the formal charges of G and H divided by r GH . This potential is composed of the contribution V sGH 0 ͑r͒ that would arise in the absence of electron correlation plus two correlation terms V sGH corr ͑r͒ and V GH disp ͑r͒, as justified in the review 16 and confirmed by the investigation 27 of the noble-gas dimers which provide a severe test of any theory. Thus,…”

Section: A Total Crystal Energy and Structurementioning

confidence: 77%

“…The damping functions 10,11,28 are assembled elsewhere. 27 The C 6 ͑GH͒ coefficients were calculated via the Slater-Kirkwood formula 29 from the polarizabilities ͑␣ G ͒ and electron numbers ͑P G ͒. The C 6 ͑XY͒ coefficients were derived 15 from the data in Table I using free ion ␣ C because there is extensive evidence 10,17,[30][31][32][33][34] that the properties of cations having p 6 outermost electronic configurations are essentially unaffected by their environment in crystal.…”

Section: The Dispersive Attractionsmentioning

confidence: 99%

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Theoretical study of the structures and electronic properties of all-surface KI and CsI nanocrystals encapsulated in single walled carbon nanotubes

Bichoutskaia

Pyper

2008

The Journal of Chemical Physics

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The structural and electronic properties of all-surface KI and CsI crystals encapsulated in single-walled carbon nanotubes are investigated theoretically with an ionic and atomistic approach using the GULP program. The short-range interactions, derived from Dirac-Fock wavefunctions, were augmented with damped dipole-dipole and dipole-quadrupole dispersive attractions. The uncorrelated interionic interactions computed using the relativistic crystal ion and relativistic integral programs accounted for anion in-crystal modifications while being exact given the ion wavefunctions. All the short-range correlation energies and the uncorrelated interactions between the ions and carbon atoms were computed using the density functional theory of a uniform electron gas of infinite extent. Unphysical self-interactions were removed by scaling the exchange interaction with a Rae factor derived from a study of the adsorption of noble gases on graphite. The predictions for the nonencapsulated crystals agreed well with those previously derived from a global analytic theory based on the Born model. This provided a good description of the contraction of the interplane distance (b) relative to the separation (R(e)) in the rocksalt structured bulk material although failing to account for the observed dilation of the intraplane ionic separations (a). Introduction of the interactions with the nanotube wall, including the ion-nanotube dispersive attractions, increased the predicted a values although these were still significantly smaller than experiment. The predicted b separations were reduced compared with those for the nonencapsulated crystals to values significantly less than observed. It is explained why introducing any ion-nanotube interactions that are sufficiently attractive as to reproduce the experimental a values must significantly underestimate the b separations. The partial transfer of anion electrons to the nanotube carbon atoms, not considered hitherto, was described by decomposing the intra-atomic interactions of both the nanotube pi- and the iodide 5p-electrons into an effective one-electron term plus the repulsion between electrons in the same orbital. These energies were derived from electronic structure computations with the additional interspecies electrostatic repulsions derived from the GULP program. Structural predictions are presented as a function of the number (n) of electrons transferred from each anion. For both KI and CsI, the structure predicted by that computation, which minimized the total energy, in contrast to the other calculations, agreed well with experiment reproducing both the significant dilation of a and the smaller contraction of b. The respective n values (n(t)) predicting the lowest energies are 0.278 and 0.285. These results are supported by comparing the experimental frequencies of Raman modes attributable to vibrations of nanotubes encapsulating KI with the corresponding frequencies for systems where independently known numbers of electrons were transferred to the nanotubes. In both the enc...

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Section: A Total Crystal Energy and Structurementioning

confidence: 77%

Section: The Dispersive Attractionsmentioning

confidence: 99%

Theoretical study of the structures and electronic properties of all-surface KI and CsI nanocrystals encapsulated in single walled carbon nanotubes

Bichoutskaia

Pyper

2008

The Journal of Chemical Physics

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“…Experimental structures were used throughout. Dimers of the noble gas elements were calculated using experimental potential well depths and geometries . The heat of formation for gaseous CsI was taken from ref .…”

Section: Methodsmentioning

confidence: 99%

“…Dimers of the noble gas elements were calculated using experimental potential well depths and geometries. 95 The heat of formation for gaseous CsI was taken from ref 96. With the exception of experimental values for H − and H 2 , all estimations for Δχ ̅ were obtained using the range-separated LC-BLYP density functional. All such calculations used the aug-cc-pVQZ basis set.…”

Section: ■ Methodologymentioning

confidence: 99%

Distinguishing Bonds

2016

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The energy change per electron in a chemical or physical transformation, ΔE/n, may be expressed as Δχ̅ + Δ(VNN + ω)/n, where Δχ̅ is the average electron binding energy, a generalized electronegativity, ΔVNN is the change in nuclear repulsions, and Δω is the change in multielectron interactions in the process considered. The last term can be obtained by the difference from experimental or theoretical estimates of the first terms. Previously obtained consequences of this energy partitioning are extended here to a different analysis of bonding in a great variety of diatomics, including more or less polar ones. Arguments are presented for associating the average change in electron binding energy with covalence, and the change in multielectron interactions with electron transfer, either to, out, or within a molecule. A new descriptor Q, essentially the scaled difference between the Δχ̅ and Δ(VNN + ω)/n terms, when plotted versus the bond energy, separates nicely a wide variety of bonding types, covalent, covalent but more correlated, polar and increasingly ionic, metallogenic, electrostatic, charge-shift bonds, and dispersion interactions. Also, Q itself shows a set of interesting relations with the correlation energy of a bond.

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“…The heavier elements present increasing penetrations as the atomic number increases, as expected for dispersion-dominated interactions. Recent calculations on Ng 2 and NgNg′ dimers (Ng = Ne–Xe) 35 give somewhat shorter distances and small positive penetrations (1–11%).…”

Section: Van Der Waals Complexes Involving Noble Gasesmentioning

confidence: 96%

The borderless world of chemical bonding across the van der Waals crust and the valence region

Álvarez¹,

Echeverría²

2023

Chem. Sci.

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The noble gas dimers as a probe of the energetic contributions of dispersion and short-range electron correlation in weakly bound systems

Cited by 9 publications

References 47 publications

Theoretical study of the structures and electronic properties of all-surface KI and CsI nanocrystals encapsulated in single walled carbon nanotubes

Theoretical study of the structures and electronic properties of all-surface KI and CsI nanocrystals encapsulated in single walled carbon nanotubes

Distinguishing Bonds

The borderless world of chemical bonding across the van der Waals crust and the valence region

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