Cluster expansion of the wavefunction. The open‐shell orbital theory including electron correlation

Locally projected molecular orbital method for molecular interactions is extended to a cluster consisting of a high-spin open-shell molecule and many closed-shell molecules. While deriving the equations, the Hartee–Fock–Roothaan equation without the orthonormal condition is obtained. The stationary conditions for molecular orbitals are expressed in a form of a generalized Brillouin condition. To obtain the molecular orbital coefficient matrix, which satisfies the stationary condition, a single Fock operator form is presented. For the locally projected molecular orbitals for the open-shell cluster, the working matrix representaion is given.

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Molecular orbital theory of the electronic structure of organic molecules. 40. Structures and energies of C1-C3 carbocations including effects of electron correlation

Journal of the American Chemical Society ◽

10.1021/ja00409a004 ◽

1981 ◽

Vol 103 (19) ◽

pp. 5649-5657 ◽

Cited By ~ 260

Author(s):

Krishnan Raghavachari ◽

Robert A. Whiteside ◽

John A. Pople ◽

Paul V. R. Schleyer

Keyword(s):

Electronic Structure ◽

Molecular Orbital ◽

Electron Correlation ◽

Organic Molecules ◽

Molecular Orbital Theory ◽

Orbital Theory

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Scalable Electron Correlation Methods. 7. Local Open-Shell Coupled-Cluster Methods Using Pair Natural Orbitals: PNO-RCCSD and PNO-UCCSD

Journal of Chemical Theory and Computation ◽

10.1021/acs.jctc.0c00192 ◽

2020 ◽

Vol 16 (5) ◽

pp. 3135-3151 ◽

Cited By ~ 3

Author(s):

Qianli Ma ◽

Hans-Joachim Werner

Keyword(s):

Electron Correlation ◽

Open Shell ◽

Coupled Cluster ◽

Natural Orbitals ◽

Correlation Methods ◽

Coupled Cluster Methods ◽

Cluster Methods

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ChemInform Abstract: PHOTOCHEMICAL AND SPECTROSCOPIE APPLICATIONS OF APPROXIMATE MOLECULAR ORBITAL THEORY PART 1, AVERAGED FIELD APPROXIMATE OPEN SHELL THEORY

Chemischer Informationsdienst ◽

10.1002/chin.197409082 ◽

1974 ◽

Vol 5 (9) ◽

pp. no-no

Author(s):

ROBERT R. BIRGE

Keyword(s):

Molecular Orbital ◽

Shell Theory ◽

Open Shell ◽

Molecular Orbital Theory ◽

Orbital Theory

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Development of the explicitly correlated Gaussian–nuclear orbital plus molecular orbital theory: Incorporation of electron–electron correlation

Chemical Physics Letters ◽

10.1016/j.cplett.2012.02.070 ◽

2012 ◽

Vol 533 ◽

pp. 100-105 ◽

Cited By ~ 14

Author(s):

Hiroaki Nishizawa ◽

Yutaka Imamura ◽

Yasuhiro Ikabata ◽

Hiromi Nakai

Keyword(s):

Molecular Orbital ◽

Electron Correlation ◽

Molecular Orbital Theory ◽

Orbital Theory ◽

Explicitly Correlated

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A Cluster Expansion Formalism for Direct Calculation of Ionisation Potential and Excitation Energy of Many Electron Systems Using H-F Ground State as Vacuum

Zeitschrift für Naturforschung A ◽

10.1515/zna-1978-1219 ◽

1978 ◽

Vol 33 (12) ◽

pp. 1549-1551

Author(s):

D. Mukherjee ◽

A. Mukhopadhyay ◽

R. K. Moitra

Keyword(s):

Excitation Energy ◽

Cluster Expansion ◽

Ground State ◽

Shell Theory ◽

State Energy ◽

Direct Calculation ◽

Electron System ◽

Open Shell ◽

Electron Systems ◽

Ionisation Potential

Abstract In this note, the authors’ recently developed non-perturbative open-shell theory is adapted for direct calculation o f ionisation potential and excitation energy of m any-electron systems. The H -F ground state is used as the “vacuum ” or “ core” in order to achieve a transparent separation o f the ground state energy. An application to a simple 4 π-electron system is discussed as an illustration o f the workability of the theory.

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