title: Exploring the potential energy surface of retinal, a comparison of the performance of different methods.
abstract: The ground state structure of retinal has been investigated. We found that DFT and CASSCF produce different results for the bond length alternation in a model system of retinal. Quantum mechanics/molecular mechanics calculations including the closest surrounding amino acids have been performed, using DFT and CASSCF to calculate the structure of retinal in the protein cavity. The planarity of the retinal molecule is affected by the surrounding protein. DFT and CASSCF produce different twist angles. The difference between CASSCF and DFT appears to be related to the positively charged nitrogen of the Schiff base, which leads to different pi-bond orders produced by the two methods.
authors.affiliation: Department of Chemistry and Bioscience, Chalmers University of Technology, SE-412 96 Göteburg, Sweden.
authors.forename: Fredrik
authors.initials: F
authors.lastname: Blomgren
authors.forename: Sven
authors.initials: S
authors.lastname: Larsson
mesh_terms: D004735:Energy Transfer; D008958:Models, Molecular; D015394:Molecular Structure; D011506:Proteins / Q000737:chemistry; D012172:Retinaldehyde / Q000737:chemistry*; D013816:Thermodynamics
chemical_list: D011506:Proteins; D012172:Retinaldehyde