A DFT study of a set of natural dyes for organic electronics

• Published in: Journal of molecular modeling 2017-12, Vol.23 (12), p.343-9, Article 343
• Main Authors: Lima, Igo T., Sousa, Leonardo, Freitas, Renato da S., Junior, Luiz Antonio Ribeiro, de Sousa Júnior, Rafael Timóteo, da Silva Filho, Demétrio A.
• Format: Article
• Language: English
• Subjects: Absorption spectra; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Computer Appl. in Life Sciences; Computer Applications in Chemistry; Conjugation; Density functional theory; Dipole moments; Molecular Medicine; Original Paper; Oscillator strengths; Theoretical and Computational Chemistry; Vertical oscillations; VI Symposium on Electronic Structure and Molecular Dynamics – VI SeedMol
• ISSN: 1610-2940; 0948-5023
• DOI: 10.1007/s00894-017-3512-8

We systematically investigate, at density functional theory level, the electronic properties of a set of ten carotenoid molecules with different conjugation length. Ground state geometries were fully optimized using both B3LYP and its long-range corrected version, i.e., the CAM-B3LYP functional. The time-dependent DFT approach (TD-DFT) was also performed for the calculation of the excited states of the optimized geometries and the results were compared to the experimental ones, when available. Our findings indicate a dependence of the transition vertical energies, oscillator strengths, and transition dipole moments on the extension of conjugation, as expected. We also investigate the impact of the intra-molecular vibrations on the absorption spectrum by means of the Franck–Condon (FC) and nuclear ensemble (NE) approach to spectra simulation. Our simulations suggest that the Franck–Condon approximation may not be suitable to appropriately characterize the vibronic progression of these molecules, whereas the NE approach provides a contribution that vary from negligible to meaningful depending on which molecule and energy region is under analysis.