Electronic Structure of Carotenoids in Natural and Artificial Photosynthesis

This chapter is about a theoretical study applied to six carotenoids present in vegetables containing carotenes and xanthophylls. Electronic properties are analyzed such as energy in frontier orbitals and the first molecular orbitals to work in the UV-Vis absorption spectroscopy. Electronic structure methodologies were used within the frame of the density functional theory (DFT) using the theoretical methods B3LYP/6-31G(d)//B3LYP/6-31G+(d,p) for ground states and B3LYP/6-31G(d)//CAM-B3LYP/6-31G+(d,p) for excited states. Results for the main absorption peak are in agreement with experimental results with a difference between zeaxanthin and violaxanthin results of 0.1 eV, approximately. The UV-Vis absorption spectra obtained for carotenoids are in good agreement with the experimental results. The possible use in energy generation systems is discussed for these systems. Diade chlorophyllide a-zeaxanthin was formed, and calculation results predicted energy transfer for these photosynthetic systems