Vibrationally Resolved Absorption and Emission Spectra of Dithiophene in the Gas Phase and in Solution by First-Principle Quantum Mechanical Calculations.

The absorption and emission spectra of dithiophene have been computed in different environments (gas phase, apolar, and polar solvents) and at different temperatures, including Duschinsky, temperature and solvent effects at full ab initio level, and considering the anharmonicity of the double well potential associated with the inter-ring torsional mode. The computed spectra are in very good agreement with the experimental ones, allowing for a complete assignment of the main vibrational features. Five different density functionals (BLYP, B3LYP, CAM-B3LYP, BHLYP, and PBE0) have been tested, and CAM-B3LYP and PBE0 are the most accurate.