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The electronic structure of low‐lying excited states of two model systems of retinal
Author(s) -
Shoda Takayuki,
Noro Takeshi,
Nomura Tsutomu,
Ohno Kimio
Publication year - 1986
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560300208
Subject(s) - excited state , protonation , schiff base , valence (chemistry) , excitation , chemistry , atomic physics , physics , stereochemistry , quantum mechanics , ion , organic chemistry
2,4‐pentadienal and 2,4,6,8‐nonatetraenal were studied as simple model systems of retinal. Four kinds of CI were performed on low‐lying excited states of 2,4‐pentadienal by using a split valence basis set. The results show that MR SD π CI is not adequate for the π–π* state and the single excitation σπ CI is a good compromise between cost and effectiveness as far as singly excited states are concerned. This CI was applied to the bigger model system. All‐ trans and 11‐ cis forms of aldehyde, Schiff base, and protonated Schiff base of the model system were studied. A fairly large energy lowering of about 1 eV of the first allowed excited state (π → π*) occurs when the Schiff base is protonated for both all‐ trans and 11‐ cis forms.