Correlated pair many-electron theory

Bartlett R J and Purvis G D 1978 Many-body perturbation theory coupled-pair many-electron theory and the importance of quadruple excitations for the correlation problem int. J. Quantum Chem. 14 561-81... 

J. Paldus, J. Cizek, and 1. Shavitt, Correlation problems in atomic and molecular systems. IV. Extended coupled-pair many-electron theory and its application to the BHs molecule. Phys. Rev. A 5, 50 (1972). 

R. J. Bartlett and G. D. Purvis, Int. ]. Quantum Chetn., 14,561 (1978). Many-Body Perturbation Theory, Coupled-Pair Many-Electron Theory, and the Importance of Quadruple Excitations for the Correlation Problem. 

Cfiek J, Paldus J (1971) Correlation problems in atomic and molecular systems III Rederivation of the coupled-pair many-electron theory using the traditional quantum chemical methods. Int J Quantum Chem 5 359-379. 

J. Cizek and J. Paldus, Int. J. Quantum Chem., 5, 359 (1971). Correlation Problems in Atomic and Molecular Systems. III. Rederivation of the Coupled-Pair Many-Electron Theory Using the Traditional Quantum Chemical Methods. 

Following the pair correlation approach of Sinanoglu,4 Cizek2 introduced the coupled-pair many-electron theory (CPMET) method, which takes into account only double excitation clusters T2. In the present paper we prefer our more systematic nomenclature for different versions of the CC method, consistently used in our previous papers. Thus the original Cizek approach will be denoted CCD (CC doubles), while its linearized version will be denoted as LCCD. By including in the CC equations single excitation clusters T, we arrive at the CCSD method, exploited in a series of papers by Bartlett and co-workers.9-11 We will also consider the linearized version of the CCSD method, LCCSD,15 the full CCSDT model that includes effects of triple excitation clusters T3, and the CCSDTQ model that also considers T. ... 

This equation, along with the definition of the symbol idS, c > given in Eq. (5.53), and the expression for the correlation energy in Eq. (5.48a) are the equations of Coupled-Pair Many-Electron Theory (CPMET), which is... 

As the next step in handling the correlation problem in larger molecules, the coupled-cluster doubles (CCD), also called coupled-pair many-electron theory (CPMET), introduced into the electronic correlation problem by Cizek, was first applied to smaller molecules and then to the nucleotide bases using localized orbitals. 

Bartlett, R. J., Purvis, G. D. (1978). Many-body perturbation theory, coupled-pair many-electron theory, and the importance of quadruple excitation for the correlation problem. International Journal of Quantum Chemistry, 14, 561-581. 

The EPC --F20r method of Sinanoglu and Pamuk is based on the Many-Electron Theory (MET) of Sinanoglu which will be noted in Section 4.G. In its simplest form, MET predicts the correlation energy to be a sum of the pair correlation energies (eqn, (4,47)) which in the LCAO approximation becomes ... 

O. Sinanoglu, Many-electron theory of atoms and molecules. I. Shells, electron pairs vs many-electron correlations, J. Chem. Phys. 36 (1962) 706. 

The "many-electron theory puts the separate treatment of (i) inner-outer, e.g. a, n, shells, and (it) localized bonds, lone pairs and ion cores on a rigorous basis both for semi- and non-empirical calculations. It shows how the following may be calculated to chemical accuracy by properly dealing with electron correlation ... 

Werner, H.-J. 2000. Perspective on Theory of Self-consistent Electron Pairs. An Iterative Method for Correlated Many-electron Wavefunctions Theor. Chem. Acc., 103, 322. 

R. Ahhichs and E. Driessler, Determination of pair natural orbitals. A new method to solve the multiconfiguration Hartree-Eock problem for two-electron wave functions, Theor. Chim. Acta, 36 (1975) 275. W. Meyer, Theory of self-consistent electron pairs. An iterative method for correlated many-electron... 

---