Author
Andrew D. Liehr
Bio: Andrew D. Liehr is an academic researcher from Bell Labs. The author has contributed to research in topics: Coupling & Degeneracy (biology). The author has an hindex of 7, co-authored 11 publications receiving 700 citations.
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TL;DR: In this article, the generalized crystal field theory of Finkelstein and Van Vleck is augmented by the introduction of spin-orbit coupling and an attempt is made to account for both the spin-allowed and spin-forbidden dn, (n = 2, 8), spectral transitions of Ni(II) and V(III) complexes.
217 citations
TL;DR: In this article, an account of the modern theories concerning the nature of the electron orbits in tetrahedral inorganic inorganic complexes of the first transition series is given, and it is shown that, although the characteristic energy spectra of these complexes may be qualitatively understood on the basis of the Bethe-Van Vleck ionic (crystal field) model, the probabilities of electronic transitions among the various stationary energy states requires the introduction of covalency, in the manner prescribed by Van Vleck (molecular orbital or "ligand field" model).
215 citations
TL;DR: Van Vleck's treatment of the Jahn-Teller effect in inorganic octahedral complexes having E g electronic states has been modified by the inclusion of additional quadratic terms.
165 citations
TL;DR: In this paper, a method for calculating the intensity of d n electronic transitions in inorganic complexes is extended to include electronic systems which exhibit configuration interaction, and the oscillator strengths of both the spin-allowed and spin-forbidden spectral transitions of divalent nickel and trivalent vanadium complex salts are computed and compared with experiment.
Abstract: The method, previously developed by the authors, for calculating the intensity of d n electronic transitions in inorganic complexes is extended to include electronic systems which exhibit configuration interaction. The oscillator strengths of both the spin-allowed and spin-forbidden spectral transitions of divalent nickel and trivalent vanadium complex salts are computed and compared with experiment. Fair agreement is found. Some critical comments concerning the relative merit of such calculations are presented. The envelope of the Ni(II) red band is elucidated in terms of the spin-orbit fine structure of the 3T1g electronic state.
37 citations
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2,329 citations
TL;DR: In the self-consistent field (SCF)-Xα scattered-wave model that is also a first-principle technique, there is no basis set problem because Schrodinger's equation for an Xα potential is numerically integrated as discussed by the authors.
Abstract: Publisher Summary The limitations of applying an ab initio linear combination of atomic orbitals (LCAO) methods to complex molecules and solids are the size of the basis sets and the number of multicenter integrals or equivalent Hartree-Fock matrix elements In the self-consistent field (SCF)-Xα scattered-wave model that is also a first-principle technique, there is no basis-set problem because Schrodinger's equation for an Xα potential is numerically integrated There are no multicenter integrals and the model is practicable in both spin-restricted and spin-unrestricted forms for polyatomic systems of considerable stereochemical complexity The SCF-Xα scattered-wave technique uses only a small fraction of the computer time required by an ab initio Hartree–Fock LCAO method The applications of the scattered-wave method to polyatomic molecules and crystals are concerned with the generation of one-electron energy and wave functions While an SCF-Xα one-electron analysis leads to an accurate quantitative description of many chemical and physical properties, it is also very important to determine the total many-electron energy As the present method leads to a rapidly convergent numerical representation of the orbital wave functions, the accuracy of the theoretical model can easily be improved via perturbation theory, when necessary Finally, the original theoretical formalism can be extended to more general forms of superposed-atom Xα potentials by means of the generalized scattered-wave theory
755 citations
TL;DR: In this article, an effective Hamiltonian of an interaction between the orbital states of the Jahn-Teller ions through a canonical transformation was obtained, which associates each electronic state with a local lattice distortion, and by use of the mean field approximation.
Abstract: A theoretical overview of the cooperative Jahn-Teller effect in the insulating phase is given. We obtain an effective Hamiltonian of an interaction between the orbital states of the Jahn-Teller ions through a canonical transformation, which associates each electronic state with a local lattice distortion, and by use of the mean field approximation. The effective Hamiltonian yields a simple unified picture of cooperative distortions of various types. The competing effect of the spin-orbit coupling is discussed also. Electron itinerancy is briefly discussed at the end.
647 citations
Abstract: The polarized absorption spectra of Ni2+ and Co2+ in crystals of ZnO, ZnS, and CdS; Ni2+ in crystals of Cs2ZnCl4 and Cs2ZnBr4; and Cu2+ in ZnO have been measured at 4°K, 77°K, and room temperature. The spectra have been interpreted by the use of crystal field theory for the states of the (3d)n configuration acted on by a potential of predominately Td symmetry. Certain details of the spectra are accounted for by smaller contributions from fields of lower symmetry, notably a C3v potential contribution for the transition metal ions in ZnO. Crystal field, electrostatic repulsion, and spin‐orbit parameters have been obtained for all these cases. An empirical correlation between the electrostatic repulsion parameter, B, for the ions in the crystals and the ligand polarizibility has been obtained. Although the configuration mixing between the states of the configurations (3d)n and (3d)n—1 (4p) has been found to give a negligible contribution to the calculated relative energies of the levels, it does partially ex...
498 citations
TL;DR: In this article, density-functional calculations using the linearized-augmented-plane-wave method were carried out for the scheelite materials in order to determine their ground-state electronic properties.
Abstract: Density-functional calculations using the linearized-augmented-plane-wave method were carried out for the scheelite materials ${\mathrm{CaMoO}}_{4},$ ${\mathrm{CaWO}}_{4},$ ${\mathrm{PbMoO}}_{4},$ and ${\mathrm{PbWO}}_{4}$ in order to determine their ground-state electronic properties. The results indicate that ${\mathrm{CaMoO}}_{4}$ and ${\mathrm{CaWO}}_{4}$ have direct band gaps at the center of the Brillouin zone, while ${\mathrm{PbMoO}}_{4}$ and ${\mathrm{PbWO}}_{4}$ have band extrema at wave vectors away from the zone center with possibly indirect band gaps. The magnitudes of the band gaps increase in the order ${\mathrm{PbMoO}}_{4}{l\mathrm{PbWO}}_{4}{l\mathrm{CaMoO}}_{4}{l\mathrm{CaWO}}_{4}.$ The valence and conduction bands near the band gap are dominated by molecular orbitals associated with the ${\mathrm{MoO}}_{4}^{\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\alpha}}}$ and ${\mathrm{WO}}_{4}^{\mathrm{\ensuremath{-}}\mathrm{\ensuremath{\alpha}}}$ ions, where $\ensuremath{\alpha}\ensuremath{\approx}2.$ The valence-band widths are 5 and 5.5 eV for the Ca and Pb materials, respectively. In the Pb materials, the Pb $6s$ states form narrow bands 1 eV below the bottom of the valence bands, and also hybridize with states throughout the valence bands, while the Pb $6p$ states hybridize with states throughout the conduction bands. In the Ca materials, the Ca $3d$ states contribute to a high density of states 3--4 eV above the bottom of the conduction bands.
370 citations