Single and double excitation configuration

Modular FORTRAN programs for performing general ab initio multireference single- and double-excitation configuration interaction, averaged coupled-pair functional and linearized couple-cluster method calculations. Cray and other versions. 

The method of single- and double-excitation configuration mixing is not size-consistent. The method remains size-inconsistent even if a multi-configurational reference function is used. For a configuration mixing calculation, with... 

Thomas et al. have carried out extensive calculations on the two unknown, unsubstituted, tetrazines, as well as on 1,2,4,5-tetrazine. SCF calculations including double zeta (DZ), and DZ plus polarization (DZP) basis sets, as well as single and double excitation configuration interaction (CSID) levels of theory were used. They have calculated relative energies (AE) by these methods, the results being given in Table 1 <9lJOC539>. 

R. J. Bartlett and I. Shavitt, Determination of the Size-Consistency Error in the Single and Double Excitation Configuration Interaction Model, Int. 

In their study of the lowest part of the Ceo Hubbard spectrum, FKS carried out single and double excited configuration interaction (SDCI) calculations. These were based on an appropriate set of reference configuration state functions constructed by means of a set of restricted Hartree-Fock (RHF) orbitals. Although, as FHS point out, a SDCI treatment is not size consistent, one can anticipate obtaining significant information with regard... 

The most accurate allowance for the correlation effects was made by Schaefer et al. [59]. An SCF calculation was supplemented by inclusion of the complete configurational interaction among all the single- and double-excited configurations (37528 for C2V structure and 74740 for the form). A lowering of the barrier was 2.9 kcal/mol and the allowance made for higher excitations added to this value 0.5 kcal/mol to give ultimately 8.1 kcal/mol. 

The 351x351 matrix included all singly and double excited configurations that are constructed from 10 MO s. Oscillator... 

DIM = diatomics-in-molecules MRDCI = multi-reference single and double excitation configuration interaction QDPT = quasi-degenerate perturbation theory. 

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