Characterization of a conical intersection between the ground and first excited state for a retinal analog

F. Molnar, M. Ben-Nun, T. J. Martínez, K. Schulten

Research output: Contribution to journalArticlepeer-review


Ab initio complete active space SCF calculations have been carried out to investigate the first excited electronic state of a retinal protonated Schiff base analog: all-trans-3,7-dimethylnona-2,4,6,8-tetraenmethylimminium cation. This model of the retinal chromophore in bacteriorhodopsin includes five conjugated double bonds as well as both pertinent backbone methyl groups. The excited state minimum that is relevant for isomerization in bacteriorhodopsin is investigated and is found to be in very close proximity to a Jahn-Teller conical intersection. The two (global) coordinates that are most effective in promoting efficient internal conversion back to the ground electronic state (by lifting the degeneracy between the ground and first excited state) are identified and discussed, and the distribution of the positive charge in the retinal analog as a function of these two coordinates is investigated. (C) 2000 Elsevier Science B.V.

Original languageEnglish (US)
Pages (from-to)169-178
Number of pages10
JournalJournal of Molecular Structure: THEOCHEM
Issue number1-3
StatePublished - Jul 14 2000


  • Bacteriorhodopsin
  • Conical intersection
  • Photoisomerization
  • Polyenes
  • Quantum chemistry
  • Retinal protonated Schiff base

ASJC Scopus subject areas

  • Physical and Theoretical Chemistry
  • Computational Theory and Mathematics
  • Atomic and Molecular Physics, and Optics


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