## Abstract Restricted‐spin coupled‐cluster single‐double plus perturbative triple excitation {RCCSD(T)} potential energy functions (PEFs) of the $ \tilde X $^2^B~2~ state of ScO~2~ and the $ \tilde X $^1^A~1~ state of ScO~2~^−^ were computed, employing the augmented correlation‐consistent polarize
Ab initio study on the electronic structures of styrene in the Franck-Condon region
✍ Scribed by Yoshiaki Amatatsu
- Publisher
- John Wiley and Sons
- Year
- 2002
- Tongue
- English
- Weight
- 201 KB
- Volume
- 23
- Category
- Article
- ISSN
- 0192-8651
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✦ Synopsis
Abstract
The electronic structures of styrene in the Franck‐Condon region have been theoretically examined by means of ab initio complete active space self‐consistent field (CASSCF) and the second order multireference Møller‐Plesset calculations. The optimized structure of styrene in S~0~ is planar but the torsional motion of the phenyl group is very floppy. The S~1~ state is assigned to the local π–π* excitation within the benzene ring. On the other hand, S~2~, above S~1~ by 0.561 eV, is assigned to a state that resembles the so‐called V‐state of ethylene. The transition intensity of S~0~–S~1~ is weak, while that of S~0~–S~2~ is strong. This is in good agreement with the experimental absorption spectrum where the S~0~–S~1~ and S~0~–S~2~ transitions are in the energy range of 290–220 nm. The optimized geometry of S~1~, characterized by an enlarged benzene ring and its vibrational analyses, further justifies the assignment of the S~1~ state. © 2002 Wiley Periodicals, Inc. J Comput Chem 9: 928–937, 2002
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