A multi-reference coupled-cluster method for molecular applications
β Scribed by William D. Laidig; Rodney J. Bartlett
- Publisher
- Elsevier Science
- Year
- 1984
- Tongue
- English
- Weight
- 680 KB
- Volume
- 104
- Category
- Article
- ISSN
- 0009-2614
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π SIMILAR VOLUMES
An extension of multi-reference coupled-cluster (MRCC) methods to include some effects of triple excitations for the direct calculation of ionization potentials is presented. A series of non-iterative methods are proposed, derived in analogy to the successful non-iterative inclusions of triple excit
It is demonstrated that standard single-reference coupled-cluster @R-CC) theories can be successfully applied to the studies of some excited states not belonging to the lowest energy in their symmetry class. The prerequisite of such applications is that a proper reference state configuration and orb
The equationof-motion coupled-cluster method (EOM-CCSD) and its quadratic CI (EOM-QCISD) variant for excited states have been implemented in the ACES II program system. Results for open-and closed-shell reference states are reported for Be, N2, CO, 02, and 0,. The results show that EOM-CCSD and EOM-
The evaluation of the energy and analytical energy gradient of the new unitary coupled-cluster method, UCC(4), are described, and initial numerical results for this method are reported. UCC(4) energies. molecular geometries, vibrational frequencies, and &pole moments are compared with results given
The recently developed state-selective (SS) multi-reference (MR) coupled-cluster (CC) method is applied to a prototype molecular system composed of eight hydrogen atoms. To obtain a better description of the zeroth-order wavefunction in the quasidegenerate region, we employ orbitals resulting from t