Correlated electron propagator theory and applications for open‐shell atoms and molecules

Born, Gregory

doi:10.1002/qua.560280303

Cited by 7 publications

(1 citation statement)

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“…They are not generally reliably applicable to atoms or molecules with open shell initial states or where the initial states have nondynamical correlation 3–26. G. Born had demonstrated that a unitary group reformulation of electron propagator theory could be used to derive the second‐order and 2p‐h Tamm–Dancoff self‐energy approximations for open‐shell applications 27–29.…”

Section: Introductionmentioning

confidence: 99%

Approximate MCSCF optimization for multiconfigurational spin‐tensor electron propagator method (MCSTEP): The vertical ionization potentials of CO, HCN, HNC, H₂CO, and O₃

Yeager

2007

Int J of Quantum Chemistry

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ABSTRACT:The multiconfigurational spin tensor electron propagator method (MCSTEP) was developed as an implementation of electron propagator/single particle Green's function methods. MCSTEP was specifically designed for open shell and highly correlated (nondynamically correlated) initial states. The initial state used in MCSTEP is typically a small complete active space (CAS) with multiconfigurational self-consistent field (MCSCF) state. In some cases, because of our use of a small CAS in MCSTEP, the Lagrangian eigenvalues of the MCSCF reference state are in an undesired order (u). The desired order (d) can usually be obtained by excluding one or more orbital rotations in MCSCF optimization between the doubly occupied and partially occupied orbitals. We systematically examine several cases where the undesired order occurs for the low-lying vertical MCSTEP ionization potentials (IPs) of the molecules CO, HCN, HNC, H 2 CO, and O 3 with our recently established CAS choices for MCSCF/MCSTEP. By excluding one or more orbital rotations between the partially and doubly occupied orbitals, an approximate MCSCF reference state with the same CAS choice is obtained for use in standard MCSTEP calculations that, in general, gives more reliable vertical MCSTEP IPs.

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Section: Introductionmentioning

confidence: 99%

Approximate MCSCF optimization for multiconfigurational spin‐tensor electron propagator method (MCSTEP): The vertical ionization potentials of CO, HCN, HNC, H₂CO, and O₃

Yeager

2007

Int J of Quantum Chemistry

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Unitary Group Approach to the Many-Electron Correlation Problem

Paldus

1992

NATO ASI Series

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The fascination with symmetry and the multitude of its manifestations in nature ean be traced back to the earliest times of human civilization. Its importance as a basic unifying principle for our understanding of the physical universe can hardly be overestimated. Initially it was of course the most conspicuous geometrical symmetry, with its unquestionable aesthetic appeal, that enabled scientists to systematically classify erystal structures and unravel the eomplexities of molecular spectra. More reeently, especially with the advent of quantum mechanics, an entirely new universe of very subtle symmetries was opened up and the intrinsic elegance and mathematical beauty of fundamental physical la ws of nature was revealed, manifesting itself in countless phenomena ranging from the discovery of antiparticles to our understanding of the periodic table and ehemical bonding. Nowadays, these limits are further expanded by probing various dynamical and gauge symmetries, quasi-symmetries and so-called supersymmetries.While classical geometrie al symmetries deal with at most three-dimensional objeets and are easily comprehended and appreciated by our senses. various symmetries that are relevant in the submicroscopic world characterize objects and concepts that can only be defined in highly-dimensional abstract spaces. Even here, however, there is a fundamental difference between present-day classical symmetries that are characterized by the so-called invariance, symmetry or degeneracy group of the Hamiltonian of the studied system (see, for example, Hamermesh, 1962;McWeeny, 1963;Chen, 1989; and references therein) and the rather recently introduced dynamical groups or spectrum generating algebras (Bohm et al., 1988) that are required to contain all the bound states of the system within a single irreducible representation (e.g., SO(4,2) or SO(2,

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Unitary Group Approach to Configuration Interaction Calculations of the Electronic Structure of Atoms and Molecules

Shavitt¹

1988

The IMA Volumes in Mathematics and Its Applications

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Correlated electron propagator theory and applications for open‐shell atoms and molecules

Cited by 7 publications

References 20 publications

Approximate MCSCF optimization for multiconfigurational spin‐tensor electron propagator method (MCSTEP): The vertical ionization potentials of CO, HCN, HNC, H₂CO, and O₃

Approximate MCSCF optimization for multiconfigurational spin‐tensor electron propagator method (MCSTEP): The vertical ionization potentials of CO, HCN, HNC, H₂CO, and O₃

Unitary Group Approach to the Many-Electron Correlation Problem

Unitary Group Approach to Configuration Interaction Calculations of the Electronic Structure of Atoms and Molecules

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Correlated electron propagator theory and applications for open‐shell atoms and molecules

Cited by 7 publications

References 20 publications

Approximate MCSCF optimization for multiconfigurational spin‐tensor electron propagator method (MCSTEP): The vertical ionization potentials of CO, HCN, HNC, H2CO, and O3

Approximate MCSCF optimization for multiconfigurational spin‐tensor electron propagator method (MCSTEP): The vertical ionization potentials of CO, HCN, HNC, H2CO, and O3

Unitary Group Approach to the Many-Electron Correlation Problem

Unitary Group Approach to Configuration Interaction Calculations of the Electronic Structure of Atoms and Molecules

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Product

Resources

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Approximate MCSCF optimization for multiconfigurational spin‐tensor electron propagator method (MCSTEP): The vertical ionization potentials of CO, HCN, HNC, H₂CO, and O₃

Approximate MCSCF optimization for multiconfigurational spin‐tensor electron propagator method (MCSTEP): The vertical ionization potentials of CO, HCN, HNC, H₂CO, and O₃