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Theoretical study of the vertical excited states of benzene, pyrimidine, and pyrazine by the symmetry adapted cluster—Configuration interaction method
Author(s) -
Li Yongjian,
Wan Jian,
Xu Xin
Publication year - 2007
Publication title -
journal of computational chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.907
H-Index - 188
eISSN - 1096-987X
pISSN - 0192-8651
DOI - 10.1002/jcc.20555
Subject(s) - excited state , pyrazine , chemistry , atomic physics , configuration interaction , singlet state , excitation , coupled cluster , symmetry (geometry) , ground state , molecular physics , physics , molecule , quantum mechanics , stereochemistry , mathematics , geometry , organic chemistry
The ground state and the excited states of benzene, pyrimidine, and pyrazine have been examined by using the symmetry adapted cluster‐configuration interaction (SAC‐CI) method. Detailed characterizations and the structures of the absorption peaks in the vacuum ultraviolet (VUV), low energy electron impact (LEEI), and electron energy loss (EEL) spectra were theoretically clarified by calculating the excitation energy and the oscillator strength for each excited state. We show that SAC‐CI has the power to well reproduce the electronic excitation spectra (VUV, LEEI, and EEL) simultaneously to an accuracy for both the singlet and the triplet excited states originated from the low‐lying π → π*, n → π*, π → σ* and n → σ* excited states of the titled compounds. The present results are compared with those of the previous theoretical studies by methods, such as EOM‐CCSD(T), STEOM‐CCSD, CASPT2 and TD‐B3LYP, etc. © 2007 Wiley Periodicals, Inc. J Comput Chem, 2007