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
Magnetic fingerprint of individual Fe4 molecular magnets under compression by a scanning tunnelling microscope.
Jacob A. J. Burgess,Luigi Malavolti,Luigi Malavolti,Valeria Lanzilotto,Matteo Mannini,Shichao Yan,Silviya Ninova,Federico Totti,Steffen Rolf-Pissarczyk,Andrea Cornia,Roberta Sessoli,Sebastian Loth +11 more
TL;DR: It is found that the exchange coupling strength within the molecule's magnetic core is significantly enhanced, and first-principles calculations support the conclusion that this is the result of confinement of the molecule in the two-contact junction formed by the microscope tip and the sample surface.
Journal ArticleDOI
Density functional study of multiplicity-changing valence and Rydberg excitations of p-block elements: delta self-consistent field, collinear spin-flip time-dependent density functional theory (DFT), and conventional time-dependent DFT.
TL;DR: A database containing 17 multiplicity-changing valence and Rydberg excitation energies of p-block elements is used to test the performance of density functional theory (DFT) with approximate density functionals for calculating relative energies of spin states, and the ΔSCF method is tested, which gives much better performance than can be obtained with time-dependent DFT.
Journal ArticleDOI
The Triplet-Singlet Gap in the m-Xylylene Radical: A Not So Simple One.
TL;DR: The use of the triplet and broken symmetry (BS) solutions for the corresponding optimized geometries obtained from B3LYP and especially M06-2X functionals provide the value of the adiabatic triplet-singlet gap closer to experiment when compared to the reported value of Wenthold, Kim, and Lineberger.
Journal ArticleDOI
Theoretical study of the magnetic interaction for M–O–M type metal oxides. Comparison of broken-symmetry approaches
Taku Onishi,Yu Takano,Yasutaka Kitagawa,Takashi Kawakami,Yasunori Yoshioka,Kizashi Yamaguchi +5 more
TL;DR: In this paper, the Hartree-Fock (UHF) and hybrid-density functional theory (DFT) calculations have been carried out for the metal oxides such as copper oxides and nickel oxides.
Posted Content
A Multireference Quantum Krylov Algorithm for Strongly Correlated Electrons
TL;DR: Preliminary benchmarks on linear H6, H8, and BeH2 indicate that MRSQK can predict the energy of these systems accurately using very compact Krylov bases.
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.