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Issue 28, 2008
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Benchmarking the performance of spin-component scaled CC2 in ground and electronically excited states

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Abstract

A generalization of the spin-component scaling and scaled opposite-spin modifications of second-order Møller–Plesset perturbation theory to the approximate coupled-cluster singles-and-doubles model CC2 (termed SCS-CC2 and SOS-CC2) is discussed and a preliminary implementation of ground and excited state energies and analytic gradients is reported. The computational results for bond distances, harmonic frequencies, adiabatic and 0–0 excitation energies are compared with experimental results to benchmark their performance. It is found that both variants of the spin-scaling increase the robustness of CC2 against strong correlation effects and lead for this method even to somewhat larger improvements than those observed for second-order Møller–Plesset perturbation theory. The spin-component scaling also enhances systematically the accuracy of CC2 for 0–0 excitation energies for π → π* and n → π* transitions, if geometries are determined at the same level.

Graphical abstract: Benchmarking the performance of spin-component scaled CC2 in ground and electronically excited states

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Publication details

The article was received on 04 Mar 2008, accepted on 15 Apr 2008 and first published on 05 Jun 2008


Article type: Paper
DOI: 10.1039/B803727B
Citation: Phys. Chem. Chem. Phys., 2008,10, 4119-4127
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    Benchmarking the performance of spin-component scaled CC2 in ground and electronically excited states

    A. Hellweg, S. A. Grün and C. Hättig, Phys. Chem. Chem. Phys., 2008, 10, 4119
    DOI: 10.1039/B803727B

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