Gauge invariance of oscillator strengths in the approximate coupled cluster triples model CC3

Filip Pawlowskia,*, Poul Jørgensena, Christof Hättigb

a Department of Chemistry, Århus University, DK-8000 Århus C, Denmark
b Forschungszentrum Karlsruhe, Institute of Nanotechnology, P.O. Box 3640, D-76021 Karlsruhe, Germany

Chem. Phys. Lett. 389, 413-420 (2004).
Received 24 February 2004; in final form 25 March 2004
Available online 20 April 2004

The gauge invariance of the oscillator strength is examined for the lowest dipole transitions in Ne, N2 and H2O using the coupled cluster model hierarchy, CCS, CC2, CCSD, and CC3, and a variety of correlation consistent basis sets. The deviations between the oscillator strengths in the different gauges decrease from CCSD to CC3 (where connected triples are included) by about the same factor as they decrease from CCS to CC2 (where connected doubles are included). The deviations are very similar in CC2 and CCSD. The quality of the oscillator strengths is improved significantly at each level in coupled cluster hierarchy, also from CC2 to CCSD, where the equivalence between the oscillator strengths in the different gauges is very similar.

*Corresponding author. Fax: +45-8619-6199
E-mail address: (F. Pawloskwi)

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