Book ChapterDOI
Algebraic Approach to Coupled Cluster Theory
Josef Paldus
- pp 207-282
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TLDR
The importance of size-extensivity in finite atomic and molecular systems was first recognized by Primas (1965), even though the term itself was coined and employed only later by Pople et al..Abstract:
With the advancement of our ability to account for many-electron correlation effects in atomic and molecular electronic structure calculations, particularly when exploring systems undergoing chemical reactions or other dissociative or associative processes, more and more emphasis is being placed on a proper size-extensive (or size-consistent) behavior of the theories employed. The requirement of size-extensivity (i.e., an exact additivity of the energy when applied to non-interacting systems) is, of course, absolutely crucial when we deal with extended systems. This is why this characteristic was automatically required in earlier developments of the general many-body perturbation theory (MBPT) by Brueckner (1955), Goldstone (1957), Hugen-holtz (1957), and others, since its primary domains of application at that time were an infinite nuclear matter (e.g., de Shalit and Feshbach, 1974; Eisenberg and Greiner, 1972) and various models of solid state physics (Hubbard, 1957,1958), notably the electron gas model (Gell-Mann and Brueckner, 1957; Quinn and Ferrell, 1958). The importance of size-extensivity in finite atomic and molecular systems was first recognized by Primas (1965), even though the term itself was coined and employed only later (Pople et al. 1976,1977,1978; Bartlett and Purvis, 1978,1980). Although both terms are often used interchangeably, we shall understand by the size-extensivity the additivity of energy for noninteracting systems or, equivalently, proportionality of the energy to the number of noninteracting systems (electrons, atoms, diatomics, etc.) involved.read more
Citations
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Journal Article
A critical assessment of coupled cluster method in quantum chemistry
Josef Paldus,Xiangzhu Li +1 more
Journal ArticleDOI
Reduced multireference CCSD method: An effective approach to quasidegenerate states
Xiangzhu Li,Josef Paldus +1 more
TL;DR: This work proposes a novel SS strategy providing a size-extensive CC formalism, while exploiting the MR model space and the corresponding excited state manifold, to preserve as much as possible the flexibility and generality offered by the general MR CC approaches.
Journal ArticleDOI
Size-consistent self-consistent configuration interaction from a complete active space
Nadia Ben Amor,Daniel Maynau +1 more
TL;DR: The size-consistent selfconsistent (SC) 2 method as discussed by the authors is based on intermediate Hamiltonians and ensures size-extensivity of any configuration interaction by correcting its diagonal elements.
References
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Journal ArticleDOI
A full coupled‐cluster singles and doubles model: The inclusion of disconnected triples
TL;DR: The coupled cluster singles and doubles model (CCSD) as discussed by the authors is derived algebraically, presenting the full set of equations for a general reference function explicitly in spin-orbital form, and the computational implementation of the CCSD model, which involves cubic and quartic terms, is discussed and results are compared with full CI calculations for H2O and BeH2.
Journal ArticleDOI
Lectures in Theoretical Physics
Journal ArticleDOI
On the Correlation Problem in Atomic and Molecular Systems. Calculation of Wavefunction Components in Ursell-Type Expansion Using Quantum-Field Theoretical Methods
TL;DR: In this article, a method for the calculation of the matrix elements of the logarithm of an operator which gives the exact wavefunction when operating on the wavefunction in the one-electron approximation is proposed.
Book
Theoretical Nuclear Physics
TL;DR: A semi-empirical basis is used to describe and correlate the known nuclear properties including the theoretical concepts, methods, and considerations which have been devised in order to interpret the experimentsl material and to advance the ability to predict and control nuclear phenomena.