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Article

The Most Stable Structure of SiC₃ Studied by Multireference Perturbation Theory with General Multiconfiguration Self-Consistent Field Reference Functions^†

Yuki Kurashige, Haruyuki Nakano,* and Kimihiko Hirao

Department of Applied Chemistry, School of Engineering, University of Tokyo, Tokyo 113-8656, Japan

J. Phys. Chem. A, 2004, 108 (15), pp 3064–3067

DOI: 10.1021/jp031133k

Publication Date (Web): January 7, 2004

†

Part of the special issue “Fritz Schaefer Festschrift”.

Corresponding author. E-mail: nakano@ccl.scc.kyushu-u.ac.jp.

Abstract

The most stable structure of the SiC₃ molecule has been investigated using second-order perturbation theory with general multiconfiguration self-consistent field reference functions (GMC−PT) and Dunning's augmented correlation-consistent polarized valence quadruple-ζ (aug-cc-pVQZ) basis set. The results showed that a closed-shell rhomboidal C₂_v isomer with a C−C transannular bond (2s) was most stable. Another closed-shell rhomboidal C₂_v isomer with a Si−C transannular bond (3s) and a linear triplet Si−C−C−C isomer (1t) was less stable by 5.3 and 6.7 kcal/mol, respectively, at the geometries optimized by the coupled cluster singles, doubles, and perturbative triples (CCSD(T)) method and the correlation-consistent polarized core-valence quadruple-ζ (cc-pCVQZ) basis set, and by 9.0 and 9.9 kcal/mol, respectively, at the geometries optimized by the fully optimized reaction space self-consistent field (FORS−SCF) method and the 6-31G(d) basis set.

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