A relativistic 4-component general-order multi-reference coupled cluster method: initial implementation and application to HBr |
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Authors: | Timo Fleig Lasse K Sørensen Jeppe Olsen |
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Institution: | 1.Department of Theoretical Chemistry, building 26.32,Heinrich Heine University Düsseldorf,Düsseldorf,Germany;2.Theoretical Chemistry, Langelandsgade 140,Aarhus University,?rhus C,Denmark |
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Abstract: | We present the initial implementation of a determinant-based general-order coupled cluster method which fully accounts for
relativistic effects within the four-component framework. The method opens the way for the treatment of multi-reference problems
through a state-selective expansion of the model space. The evaluation of the coupled cluster vector function is carried out
via relativistic configuration interaction expansions. The implementation is based on a large-scale configuration interaction
technique, which may efficiently treat long determinant expansions of more than 108 terms. We demonstrate the capabilities of the new method in calculations of complete potential energy curves of the HBr molecule.
The inclusion of spin–orbit interaction and higher excitations than coupled cluster double excitations, either by multi-reference
model spaces or the inclusion of full iterative triple excitations, lead to highly accurate results for spectral constants
of HBr.
An erratum to this article can be found at |
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Keywords: | Relativistic 4-component Multi-reference Coupled cluster Spectroscopic properties |
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