Two triple excitation equation-of-motion coupled-cluster (EOM-CC) methods for excitation energies are derived, implemented, and tested. They are excited state analogues of the CC singles, doubles, and linearized triples (CCSDT-1) iterative method and the CCSD method with a noniterative inclusion of
Coupled-cluster method for excitation energies
β Scribed by Frank E. Harris
- Publisher
- John Wiley and Sons
- Year
- 2009
- Tongue
- English
- Weight
- 460 KB
- Volume
- 12
- Category
- Article
- ISSN
- 0020-7608
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π SIMILAR VOLUMES
Equations are derived for the derivatives of the contribution of triple excitations to the energy for the fourth-order many-body perturbation theory (MBPT (4) ), quadratic configuration interaction with singles, doubles, and noniterative triples (QCISD(T ) ), and coupled-cluster with singles, double
An open-shell coupled-cluster method for the direct calculation of excitation energies is presented. As a first test, applications to atomic Be and Ne are carried out, with exact inclusion of T, and T2 operators and lowest-order inclusion of T3. Quasicomplete model spaces are used. Two ionization p
A correction for the effects of connected triple excitations to the coupled-cluster singles and doubles energy is studied. The approach relies on the fact that the ground-state coupled-cluster energy may be viewed as an eigenvalue of an Ε½ . effective similarity transformed Hamiltonian with associate