Theoretical Investigation of Carotenoid Ultraviolet Spectra

We have determined the pi band-gaps of the main carotenoids present in poly(methyl)methacrylate/buriti blends, namely, trans-beta-carotene, 13-cis-beta-carotene, 9-cis-beta-carotene, phytofluene, and zeaxanthin. Semiempirical, model Hamiltonian, and density functional calculations were carried out to study these structures. The geometries were fully optimized using AM1, PM3, and B3LYP/6-31G(d,p) methods. The TD-DFT and ZINDO/S methods were applied for the calculation of the electronic absorption spectra of the optimized B3LYP geometries. The calculated spectra using the polarizable continuum model for the solvent effects were compared with the available experimental. (C) 2008 Wiley Periodicals, Inc. Int J Quantum Chem 109: 739-745, 2009