Excited states in the multireference state-specific coupled-cluster theory with the complete active space reference

Vladimir V. Ivanov, Ludwik Adamowicz, Dmitry I. Lyakh

Research output: Contribution to journalArticle

19 Citations (Scopus)

Abstract

The recently proposed multireference state-specific coupled-cluster theory with the complete active space reference has been used to study electronically excited states with different spatial and spin symmetries. The algorithm for the method has been obtained using the computerized approach for automatic generation of coupled-cluster diagrams with an arbitrary level of the electronic excitation from a formal reference determinant. The formal reference is also used to generate the genuine reference state in the form of a linear combination of determinants contracted to a configuration with the spin and spatial symmetries of the target state. The natural-orbital expansions of the one-electron configuration inferaction density matrix allowed us to obtain the most compact orbital space for the expansion of the reference function. We applied our approach in the calculations of singlet and triplet states of different spatial symmetries of the water molecule. The comparisons of the results with values obtained using other many-particle methods and with the full configuration interaction results demonstrate good ability of the approach to deal with electronic excited states.

Original languageEnglish (US)
Article number184302
JournalThe Journal of Chemical Physics
Volume124
Issue number18
DOIs
StatePublished - 2006

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Excited states
Crystal symmetry
excitation
determinants
symmetry
Molecules
Electrons
Water
orbitals
expansion
configurations
electronics
configuration interaction
atomic energy levels
diagrams
water
molecules
electrons

ASJC Scopus subject areas

  • Atomic and Molecular Physics, and Optics

Cite this

Excited states in the multireference state-specific coupled-cluster theory with the complete active space reference. / Ivanov, Vladimir V.; Adamowicz, Ludwik; Lyakh, Dmitry I.

In: The Journal of Chemical Physics, Vol. 124, No. 18, 184302, 2006.

Research output: Contribution to journalArticle

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