Formulation and implementation of a relativistic unrestricted coupled-cluster method including noniterative connected triples
- 15 November 1996
- journal article
- research article
- Published by AIP Publishing in The Journal of Chemical Physics
- Vol. 105 (19), 8769-8776
- https://doi.org/10.1063/1.472655
Abstract
The formalism for a relativistic open‐shell CCSD(T) method is presented and implemented in a computer program, RELCCSD. The code can be used for calculations with 2‐ or 4‐component relativistic reference wave functions and allows a full inclusion of the spin–orbit coupling. The code is interfaced to the MOLFDIR program system. We illustrate its use with ab initio calculations of the fine structure splittings of Cl, FO, ClO, O+ 2, and O− 2. The triples correction is found to make a large contribution to the Cl atom splitting, which is within 23 cm−1, of the experimental value. The molecular results are within 4 cm−1 of the experimental values where these are available. The value for FO is predicted to be −195±4 cm−1, in good agreement with experiment.Keywords
This publication has 42 references indexed in Scilit:
- An exact separation of the spin-free and spin-dependent terms of the Dirac–Coulomb–Breit HamiltonianThe Journal of Chemical Physics, 1994
- Relativistic regular two-component HamiltoniansThe Journal of Chemical Physics, 1993
- Coupled-cluster approach to molecular structure and spectra: a step toward predictive quantum chemistryThe Journal of Physical Chemistry, 1989
- Regular Two-Component Pauli-Like Effective Hamiltonians in Dirac TheoryPhysica Scripta, 1986
- Diagonalisation of the Dirac Hamiltonian as a basis for a relativistic many-body procedureJournal of Physics B: Atomic and Molecular Physics, 1986
- A full coupled-cluster singles and doubles model: The inclusion of disconnected triplesThe Journal of Chemical Physics, 1982
- Quantum electrodynamical corrections to the fine structure of heliumAnnals of Physics, 1974
- Correlation problems in atomic and molecular systems III. Rederivation of the coupled‐pair many‐electron theory using the traditional quantum chemical methodstInternational Journal of Quantum Chemistry, 1971
- On the Use of the Cluster Expansion and the Technique of Diagrams in Calculations of Correlation Effects in Atoms and MoleculesAdvances in Chemical Physics, 1969
- On the Dirac Theory of Spin 1/2 Particles and Its Non-Relativistic LimitPhysical Review B, 1950