Journal ArticleDOI
Electronic structure of the alpha and beta isomers of [Mo(8)O(26)](4-).
TLDR
In this article, the structure and bonding in alpha and beta octamolybdate anions have been investigated using density functional methods, and good computational-experimental agreement for the geometrical parameters has been obtained.Abstract:
The structure and bonding in alpha and beta octamolybdate anions have been investigated using density functional methods. In general, good computational-experimental agreement for the geometrical parameters has been obtained. The electronic structure of the anions has been probed with molecular orbital and Mulliken-Mayer methods. All Mo-O interactions have been found to be predominantly d(Mo)-p(O) in character. Several multicentered molecular orbitals can be described as sigma or pi closed-loop structures, but the proposed connection with the stability of the polyanions is not completely supported by the calculations. Mayer indexes correspond to fractional multiple character for terminal bonds and approximately single or low-order character for bridging bonds, in accordance with structural and bond valence results. The valency analysis has yielded similar overall bonding capacity for the various oxygen atoms. A distribution of the negative charge over all types of oxygen sites and metal charges considerably smaller than the formal oxidation states have been obtained from the Mulliken analysis.read more
Citations
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Structure, properties and reactivity of polyoxometalates: a theoretical perspective
TL;DR: The progress achieved during the past decade has been spectacular and herein the authors critically review the most important papers to provide the reader with an almost complete perspective of the field.
Journal ArticleDOI
Calculating the partitioning of the isotopes of Mo between oxidic and sulfidic species in aqueous solution
TL;DR: In this paper, the isotopic fractionation equilibrium constants for the isotopes 92Mo and 100Mo between oxic sediments were derived from the calculated vibrational, rotational and translational contributions to the free energy in the gas-phase using quantum methods.
Journal ArticleDOI
Density functional study of the vibrational frequencies of α-Keggin heteropolyanions
TL;DR: In this article, the vibrational spectra of α-Keggin heteropolyanions have been calculated using density functional theory and the results confirm the high symmetry for these anions suggested by previous geometry calculations.
Journal ArticleDOI
Prediction of remarkably large second-order nonlinear optical properties of organoimido-substituted hexamolybdates.
Muhammad Ramzan Saeed Ashraf Janjua,Chun-Guan Liu,Wei Guan,Jia Zhuang,Shabbir Muhammad,Li-Kai Yan,Zhong-Min Su +6 more
TL;DR: Analysis of the major contributions to the beta(vec) value suggests that the charge transfer from polyanion to organic segment (D-A) along the z-axis plays the key role in NLO response; the polyanions acts as a donor whereas organoimido acts as an acceptor in all the studied systems.
Journal ArticleDOI
Theoretical study on the electronic spectrum and the origin of remarkably large third-order nonlinear optical properties of organoimide derivatives of hexamolybdates.
TL;DR: The organoimide derivatives of hexamolybdates may comprise a new promising class of nonlinear optical materials from the standpoint of large values, small dispersion behavior, and high transparency.
References
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Journal ArticleDOI
Self-Consistent Equations Including Exchange and Correlation Effects
Walter Kohn,L. J. Sham +1 more
TL;DR: In this paper, the Hartree and Hartree-Fock equations are applied to a uniform electron gas, where the exchange and correlation portions of the chemical potential of the gas are used as additional effective potentials.
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Density-functional exchange-energy approximation with correct asymptotic behavior.
TL;DR: This work reports a gradient-corrected exchange-energy functional, containing only one parameter, that fits the exact Hartree-Fock exchange energies of a wide variety of atomic systems with remarkable accuracy, surpassing the performance of previous functionals containing two parameters or more.
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Ab Initio Calculation of Vibrational Absorption and Circular Dichroism Spectra Using Density Functional Force Fields
TL;DR: In this article, the unpolarized absorption and circular dichroism spectra of the fundamental vibrational transitions of the chiral molecule, 4-methyl-2-oxetanone, are calculated ab initio using DFT, MP2, and SCF methodologies and a 5S4P2D/3S2P (TZ2P) basis set.
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Accurate spin-dependent electron liquid correlation energies for local spin density calculations: a critical analysis
TL;DR: The authors assess various approximate forms for the correlation energy per particle of the spin-polarized homogeneous electron gas that have frequently been used in applications of the local spin density a...
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Density-functional approximation for the correlation energy of the inhomogeneous electron gas
TL;DR: Numerical results for atoms, positive ions, and surfaces are close to the exact correlation energies, with major improvements over the original LM approximation for the ions and surfaces.