Journal ArticleDOI
Open‐shell coupled‐cluster method: Electron affinities of Li and Na
TLDR
In this paper, the open-shell coupled-cluster method is applied to the electron affinities of Li and Na, which are calculated in two ways: as the ionization potential of the anions or as the energy of adding the second electron to the cations.Abstract:
The open-shell coupled-cluster method and the diagrams needed for its implementation are described. The method is applied to the electron affinities of Li and Na, which are calculated in two ways: as the ionization potential of the anions or as the energy of adding the second electron to the cations. The two schemes give essentially the same results, in very good agreement (<0.02 eV) with experiment. Three-body effects are negligible.read more
Citations
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Journal ArticleDOI
The Fock space coupled cluster method: theory and application
TL;DR: The Fock space coupled cluster method and its application to atomic and molecular systems are described in this article, where the importance of conserving size extensivity is demonstrated by the electron affinities of the alkali atoms.
Journal ArticleDOI
Symmetry breaking in radicals: NO2, NS2 and NO3
TL;DR: In this article, the equilibrium configuration of the ground and two excited doublet states of the NO2, NS2 and NO3 radicals was investigated using coupled-cluster method with single and double excitations.
Book ChapterDOI
A Critical Assessment of Multireference-Fock Space CCSD and Perturbative Third-Order Triples Approximations for Photoelectron Spectra and Quasidegenerate Potential Energy Surfaces
TL;DR: In this article, the Fock space coupled cluster (FSCCSDT) method was used for ionization potential (IP) and potential energy surface (PES) problems, including all single, double, and triple excitations.
Journal ArticleDOI
Multireference Fock space coupled cluster method in the effective and intermediate Hamiltonian formulation for the (2,0) sector
TL;DR: The proposed method, IH-FS-CCSD (2,0), is rigorously size-extensive, easy to code, and numerically very efficient with the results comparable or slightly better than equation-of-motion ones at the CCSDT (T--triples) level.
Journal ArticleDOI
The ground state geometry of the NO3 radical
TL;DR: In this article, a coupled-cluster method with single and double excitations (CCSD) was used to investigate the equilibrium configuration and vibrational frequencies of the NO 3 radical.
References
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Journal ArticleDOI
Self‐consistent molecular orbital methods. XX. A basis set for correlated wave functions
TL;DR: In this article, a contract Gaussian basis set (6•311G) was developed by optimizing exponents and coefficients at the Mo/ller-Plesset (MP) second-order level for the ground states of first-row atoms.
Journal ArticleDOI
Self‐consistent molecular orbital methods. XXIII. A polarization‐type basis set for second‐row elements
Michelle Francl,William J. Pietro,Warren J. Hehre,J. Stephen Binkley,Mark S. Gordon,Douglas J. DeFrees,John A. Pople +6 more
TL;DR: In this article, the 631G* and 6 31G* basis sets were extended through the second-row of the periodic table and the Hartree-Fock wave functions were used to obtain the equilibrium geometries for one-heavy-atom hydrides.
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
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.