Abstract
A general procedure is introduced for calculation of the electron correlation energy, starting from a single Hartree–Fock determinant. The normal equations of (linear) configuration interaction theory are modified by introducing new terms which are quadratic in the configuration coefficients and which ensure size consistency in the resulting total energy. When used in the truncated configuration space of single and double substitutions, the method, termed QCISD, leads to a tractable set of quadratic equations. The relation of this method to coupled-cluster (CCSD) theory is discussed. A simplified method of adding corrections for triple substitutions is outlined, leading to a method termed QCISD(T). Both of these new procedures are tested (and compared with other procedures) by application to some small systems for which full configuration interaction results are available.
Keywords
Configuration interactionCoupled clusterQuadratic equationConfiguration spaceElectronic correlationConsistency (knowledge bases)Full configuration interactionMathematicsSpace (punctuation)Set (abstract data type)Statistical physicsPhysicsElectronApplied mathematicsQuantum mechanicsComputer scienceGeometryMolecule
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Publication Info
- Year
- 1987
- Type
- article
- Volume
- 87
- Issue
- 10
- Pages
- 5968-5975
- Citations
- 4496
- Access
- Closed
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Cite This
John A. Pople,
Martin Head‐Gordon,
Krishnan Raghavachari
(1987).
Quadratic configuration interaction. A general technique for determining electron correlation energies.
The Journal of Chemical Physics
, 87
(10)
, 5968-5975.
https://doi.org/10.1063/1.453520
Identifiers
- DOI
- 10.1063/1.453520