Formulation and implementation of a relativistic unrestricted coupled-cluster method including noniterative connected triples

L. Visscher, T.J. Lee, K.G. Dyall

Research output: Contribution to JournalArticleAcademicpeer-review

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.
Original languageEnglish
Pages (from-to)8769-8776
Number of pages8
JournalJournal of Chemical Physics
Volume105
Issue number19
DOIs
Publication statusPublished - 15 Nov 1996
Externally publishedYes

Cite this

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title = "Formulation and implementation of a relativistic unrestricted coupled-cluster method including noniterative connected triples",
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.",
author = "L. Visscher and T.J. Lee and K.G. Dyall",
year = "1996",
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Formulation and implementation of a relativistic unrestricted coupled-cluster method including noniterative connected triples. / Visscher, L.; Lee, T.J.; Dyall, K.G.

In: Journal of Chemical Physics, Vol. 105, No. 19, 15.11.1996, p. 8769-8776.

Research output: Contribution to JournalArticleAcademicpeer-review

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T1 - Formulation and implementation of a relativistic unrestricted coupled-cluster method including noniterative connected triples

AU - Visscher, L.

AU - Lee, T.J.

AU - Dyall, K.G.

PY - 1996/11/15

Y1 - 1996/11/15

N2 - 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.

AB - 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.

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