A time-dependent density-functional theory and complete active space self-consistent field method study of vibronic absorption and emission spectra of coumarin

作者：Li, Junfeng; Rinkevicius, Zilvinas^*; Cao, Zexing

来源：Journal of Chemical Physics, 2014, 141(1): 014306.

DOI：10.1063/1.4885845

• MULTIREFERENCE PERTURBATION-THEORY
• TD-DFT
• EXCITED-STATES
• FLUORESCENCE
• DERIVATIVES

Time-dependent density-functional theory (TD-DFT) and complete active space multiconfiguration self-consistent field (CASSCF) calculations have been used to determine equilibrium structures and vibrational frequencies of the ground state and several singlet low-lying excited states of coumarin. Vertical and adiabatic transition energies of S-1, S-2, and S-3 have been estimated by TD-B3LYP and CASSCF/PT2. Calculations predict that the dipole-allowed S-1 and S-3 states have a character of (1)(pi pi*), while the dipole-forbidden (1)(n pi*) state is responsible for S-2. The vibronic absorption and emission spectra of coumarin have been simulated by TD-B3LYP and CASSCF calculations within the Franck-Condon approximation, respectively. The simulated vibronic spectra show good agreement with the experimental observations available, which allow us to reasonably interpret vibronic features in the S-0 -> S-1 and S-0 -> S-3 absorption and the S-0 <- S-1 emission spectra. Based on the calculated results, activity, intensity, and density of the vibronic transitions and their contribution to the experimental spectrum profile have been discussed.

• 出版日期2014-7-7
• 单位厦门大学