On methods for converging open-shell Hartree-Fock wave-functions

Guest, Martyn F.; Saunders, V. R.

doi:10.1080/00268977400102171

Cited by 211 publications

(98 citation statements)

References 10 publications

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“…One approach, the maximum overlap method, 53 chooses the new occupied orbitals to be those have a maximum overlap with the old occupied orbitals during the SCF process. We have used a carefully chosen level shift 54,55 parameter in the STEX calculations reported here to guarantee that we target the right core-excited state. Upon exciting a core electron to a virtual orbital, we obtain an open-shell singlet state…”

Section: A the Stex Methodsmentioning

confidence: 99%

Core and valence excitations in resonant X-ray spectroscopy using restricted excitation window time-dependent density functional theory

Zhang

Biggs

Healion

et al. 2012

The Journal of Chemical Physics

107

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We report simulations of X-ray absorption near edge structure (XANES), resonant inelastic X-ray scattering (RIXS) and 1D stimulated X-ray Raman spectroscopy (SXRS) signals of cysteine at the oxygen, nitrogen, and sulfur K and L 2,3 edges. Comparison of the simulated XANES signals with experiment shows that the restricted window time-dependent density functional theory is more accurate and computationally less expensive than the static exchange method. Simulated RIXS and 1D SXRS signals give some insights into the correlation of different excitations in the molecule.

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Section: A the Stex Methodsmentioning

confidence: 99%

Core and valence excitations in resonant X-ray spectroscopy using restricted excitation window time-dependent density functional theory

Zhang

Biggs

Healion

et al. 2012

The Journal of Chemical Physics

107

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“…Since the pioneering work by Roothaan [85], the solution of the ROHF problem has been attempted by distinct means, ranging from directly tackling the ROHF equations in (112) explicitly forcing the orthogonality constraints [86,87], to the construction of a so-called unified coupling operator [85,89,90], which allows to turn the ROHF scheme into a single pseudoeigenvalue problem at the price of introducing certain ambiguities in the one-electron orbital energies [82,88]. The details and subtleties involved in these issues are beyond the scope of a review of the fundamental topics such as this one.…”

Section: The Hartree-fock Approximationmentioning

confidence: 99%

A mathematical and computational review of Hartree–Fock SCF methods in quantum chemistry

Echenique¹,

Alonso²

2007

Molecular Physics

101

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We present here a review of the fundamental topics of Hartree-Fock theory in Quantum Chemistry. From the molecular Hamiltonian, using and discussing the Born-Oppenheimer approximation, we arrive to the Hartree and Hartree-Fock equations for the electronic problem. Special emphasis is placed in the most relevant mathematical aspects of the theoretical derivation of the final equations, as well as in the results regarding the existence and uniqueness of their solutions. All Hartree-Fock versions with different spin restrictions are systematically extracted from the general case, thus providing a unifying framework. Then, the discretization of the one-electron orbitals space is reviewed and the Roothaan-Hall formalism introduced. This leads to a exposition of the basic underlying concepts related to the construction and selection of Gaussian basis sets, focusing in algorithmic efficiency issues. Finally, we close the review with a section in which the most relevant modern developments (specially those related to the design of linear-scaling methods) are commented and linked to the issues discussed. The whole work is intentionally introductory and rather self-contained, so that it may be useful for non experts that aim to use quantum chemical methods in interdisciplinary applications. Moreover, much material that is found scattered in the literature has been put together here to facilitate comprehension and to serve as a handy reference.

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“…At present, however, the algorithm described above works fairly well. This is especially true for the MCSCF calculation where the AO integrals (for a disk based method) are only calculated once for each MCSCF energy (which may involve approximately [10][11][12][13][14][15][16][17][18][19][20] iterations to obtain convergence). For more information about the transformation, the reader is referred to reference 2a.…”

Section: Integral Transformationmentioning

confidence: 99%