Journal ArticleDOI
Valence bond description of antiferromagnetic coupling in transition metal dimers
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TLDR
In this paper, a single configuration model containing nonorthogonal magnetic orbitals is developed to represent the important features of the antiferromagnetic state of a transition metal dimer.Abstract:
A single configuration model containing nonorthogonal magnetic orbitals is developed to represent the important features of the antiferromagnetic state of a transition metal dimer. A state of mixed spin symmetry and lowered space symmetry is constructed which has both conceptual and practical computational value. Either unrestricted Hartree–Fock theory or spin polarized density functional theory, e.g., Xα theory, can be used to generate the mixed spin state wave function. The most important consequence of the theory is that the Heisenberg exchange coupling constant J can be calculated simply from the energies of the mixed spin state and the highest pure spin multiplet.read more
Citations
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Journal ArticleDOI
Structural Analysis of the Mn(IV)/Fe(III) Cofactor of Chlamydia trachomatis Ribonucleotide Reductase by Extended X-ray Absorption Fine Structure Spectroscopy and Density Functional Theory Calculations
Jarod M. Younker,Courtney M. Krest,Wei Jiang,Carsten Krebs,J. Martin Bollinger,Michael Green +5 more
TL;DR: Extended X-ray absorption fine structure (EXAFS) spectroscopy and density functional theory (DFT) calculations are used to postulate a structure for this cofactor, which uses a stable Mn(IV)/Fe(III) cofactor to initiate nucleotide reduction by a free-radical mechanism.
Journal ArticleDOI
Magnetic exchange interactions in perfluorophenyl dithiadiazolyl radicals
TL;DR: In this paper, the authors show that the dominant exchange pathway would appear to be a direct exchange mechanism between radical centres, with orthogonality of the singly occupied molecular orbitals (SOMOs) favouring ferromagnetic interactions.
Journal ArticleDOI
Electronic Structures of Homoleptic [tris(2,2'-bipyridine)M]n Complexes of the Early Transition Metals (M = Sc, Y, Ti, Zr, Hf, V, Nb, Ta; N = 1+, 0, 1-, 2-, 3-): An Experimental and Density Functional Theoretical Study
TL;DR: It is shown that in the [Y(bpy)(3)](m) series the central ion possesses an invariant +III oxidation state and that the three successive one-electron redox processes that comprise the series are solely ligand-based, yielding three (bpy(•))(1-) radical anions in the neutral complex through to three diamagnetic dianion in the trianion.
Journal ArticleDOI
Correlated-Participating-Orbitals Pair-Density Functional Method and Application to Multiplet Energy Splittings of Main-Group Divalent Radicals.
TL;DR: The accuracy of the translated Perdew-Burke-Ernzerhof (tPBE) on-top pair-density functionals with ext-CPO active space is even better than some of the more accurately parametrized exchange-correlation density functionals that were tested; this is very encouraging for MC-PDFT theory.
Journal ArticleDOI
Metal substitution in the active site of nitrogenase MFe7S9 (M = Mo4+, V3+, Fe3+)
TL;DR: In this paper, spin-polarized broken-symmetry (BS) density functional theory (DFT) calculations are used to assess which of the two possible metal-ion valence assignments (4Fe2+4Fe3+) for the iron-only cofactor (FeFeco) best represents the resting state.
References
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Journal ArticleDOI
New Approach to the Theory of Superexchange Interactions
TL;DR: In this article, the theory of indirect exchange in poor conductors is examined from a new viewpoint in which the $d$ (or $f$) shell electrons are placed in wave functions assumed to be exact solutions of the problem of a single $d-electron in the presence of the full diamagnetic lattice.
Journal ArticleDOI
Orbital interactions in metal dimer complexes
TL;DR: In this paper, the effect of geometrical distortions, electronegativity, and variation of substituents on the magnetic interaction in dimeric systems is examined in detail for singly bridged L,M-X-ML, (n = 3, 4, 5); Cu~C16~ and other doubly bridging species where the bridging ligands are halogens, OR, pyridine N-oxides, oxalate, squarate; and the acetate bridged dimers C u ~ (R C 0 0 ) 4.
Journal ArticleDOI
Quantum Theory of Many-Particle Systems. III. Extension of the Hartree-Fock Scheme to Include Degenerate Systems and Correlation Effects
TL;DR: In this paper, it was shown that if the total wave function is approximated by a projection of a single determinant, the description of the system may be reduced to the ordinary Hartree-Fock scheme treating this determinant.
Book ChapterDOI
Scattered-Wave Theory of the Chemical Bond
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.