Bond functions and many-body effects of the helium trimer

Shalabi, A.S.; El‐Nahas, Ahmed M.

doi:10.1007/s002140050224

Cited by 5 publications

(1 citation statement)

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“…The appreciable change of electronic configuration with respect to the free atom configuration 4s 2 3d 5 is the hybridization between 4s and 3d orbitals with negligible contribution of the 4p sub-shell and no appreciable charge transfer from 3d orbitals. This is clear from the results presented in tables 5 and 6 which have been obtained from an NBO population analysis [59][60][61][62][63][64]. This analysis reveals that the electronic configuration of the adsorbed metal represents a qualitative change with respect to that of the free metal.…”

Section: Resultsmentioning

confidence: 56%

Spin transition energies of Cr in complexes and CO binding with Cr deposited on S²⁻and Se²⁻anion impurities of MgO (001) surface density functional theory calculations

Shalabi¹,

Aal²,

Assem³

et al. 2012

Phys. Scr.

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An attempt has been made to analyze the spin transition energies of Cr, a representative example of transition metals, in a variety of complexes formed at regular (001) surfaces of MgO, as well as the adsorption of CO by means of hybrid density functional theory calculations and embedded cluster models. Clusters of moderate sizes are embedded in the simulated Coulomb fields that closely approximate the Madelung fields of the host surfaces. While the spin states of Cr are reduced and preserved in all complexes, be they defect-free or-defect containing, the combined effects of the adsorbate and the substrate in the defect-free OC.Cr.Mg9O13O2− complex were strong enough to favor the low-spin state and to quench the spin. The deposited Cr atoms enhance the adsorption of CO. The significant weakening of bond strength between OC and Cr in complexes supports the concept of bond order conservation. The natural bond orbital (NBO) analysis reveals that the electronic structure of the adsorbed metal represents a qualitative change with respect to that of the free metal. The effects of spin contamination on the geometry, Mulliken charges and adsorption energy are examined. The binding of CO precursor is dominated by the E (i)Cr.CO pairwise additive components, and the role of the support was not restricted to supporting the metal. Relations are established between the process of spin transition and the energy gaps between frontier orbitals. The results show that the spin state of adsorbed metal atoms on oxide supports and the role of precursor molecules in the properties of spin transition energies of Cr in complexes need to be explicitly taken into account.

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Section: Resultsmentioning

confidence: 56%

Spin transition energies of Cr in complexes and CO binding with Cr deposited on S²⁻and Se²⁻anion impurities of MgO (001) surface density functional theory calculations

Shalabi¹,

Aal²,

Assem³

et al. 2012

Phys. Scr.

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Comparative study of errors in HeH? interaction energy calculations

Shalabi

Eid

Kamel

et al. 1998

Int. J. Quant. Chem.

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Basis set truncation error BSTE , size extensivity Error SEE , zero point Ž . Ž . y vibrational energy ZPVE , and basis set superposition error BSSE of HeH weak van der Waals interaction energy were determined and compared at the self-consistent field Ž . Ž . Ž . SCF , many-body perturbation theory MBPT , and coupled cluster CC methods using even-tempered functions. Isotope substitution effects and the role of bond function Ž . augmentation were taken into account. Apart from core correlation energy error CCEE , which is absent from HeH y interaction energy, the results confirm that BSTE is the most Ž . important source of error, followed by SEE of the truncated configuration interaction CI expansion, ZPVE and BSSE in a descending order. Introducing quadrable excitations to the truncated CI expansion reduces the magnitude of SEE by ; 45.7%, and BSSE correction is not necessary even at the electron correlation level. While bond function augmentation reduces BSSE at the Hartree᎐Fock, it has an oscillating behavior at the electron correlation level.

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Characterization of van der Waals interaction potentialsD4h andTd configurations of He4

Shalabi

Nour

Halim

2000

Int. J. Quant. Chem.

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Bond functions and many-body effects of the helium trimer

Cited by 5 publications

References 10 publications

Spin transition energies of Cr in complexes and CO binding with Cr deposited on S²⁻and Se²⁻anion impurities of MgO (001) surface density functional theory calculations

Spin transition energies of Cr in complexes and CO binding with Cr deposited on S²⁻and Se²⁻anion impurities of MgO (001) surface density functional theory calculations

Comparative study of errors in HeH? interaction energy calculations

Characterization of van der Waals interaction potentialsD4h andTd configurations of He4

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Bond functions and many-body effects of the helium trimer

Cited by 5 publications

References 10 publications

Spin transition energies of Cr in complexes and CO binding with Cr deposited on S2−and Se2−anion impurities of MgO (001) surface density functional theory calculations

Spin transition energies of Cr in complexes and CO binding with Cr deposited on S2−and Se2−anion impurities of MgO (001) surface density functional theory calculations

Comparative study of errors in HeH? interaction energy calculations

Characterization of van der Waals interaction potentialsD4h andTd configurations of He4

Contact Info

Product

Resources

About

Spin transition energies of Cr in complexes and CO binding with Cr deposited on S²⁻and Se²⁻anion impurities of MgO (001) surface density functional theory calculations

Spin transition energies of Cr in complexes and CO binding with Cr deposited on S²⁻and Se²⁻anion impurities of MgO (001) surface density functional theory calculations