Semiclassical Approach to Photophysics Beyond Kasha's Rule and Vibronic Spectroscopy Beyond the Condon Approximation. The Case of Azulene

Abstract

Azulene is a prototypical molecule with an anomalous fluorescence from the second excited electronic state, thus violating Kasha's rule, and with an emission spectrum that cannot be understood within the Condon approximation. To better understand photophysics and spectroscopy of azulene and other non-conventional molecules, we develop a systematic, general, and efficient computational approach combining semiclassical dynamics of nuclei with ab initio electronic structure. First, to analyze the nonadiabatic effects, we complement the standard population dynamics by a rigorous measure of adiabaticity, estimated with the multiple-surface dephasing representation. Second, we propose a new semiclassical method for simulating non-Condon spectra, which combines the extended thawed Gaussian approximation with the efficient single-Hessian approach. S${}_1\leftarrow$ S${}_0$ and S${}_2\leftarrow$ S${}_0$ absorption and S${}_2\to$ S${}_0$ emission spectra of azulene, recorded in a new set of experiments, agree very well with our calculations. We find that accuracy of the evaluated spectra requires the treatment of anharmonicity, Herzberg--Teller, and mode-mixing effects.

Added Fig. 1 and Eq. (5), modified figure captions. Last 15 pages contain the Supporting Information

References in corpus (8)

• Landau-Zener type surface hopping algorithms
• On-the-fly ab initio semiclassical dynamics: Identifying degrees of freedom essential for emission spectra of oligothiophenes
• On-the-fly ab initio semiclassical evaluation of absorption spectra of polyatomic molecules beyond the Condon approximation
• An Effective Semiclassical Approach to IR Spectroscopy
• On-the-fly ab initio three thawed Gaussians approximation: A semiclassical approach to Herzberg-Teller spectra
• Vibrational Investigation of Nucleobases by Means of Divide and Conquer Semiclassical Dynamics
• Semiclassical vibrational spectroscopy with Hessian databases
• Evaluation of the importance of spin-orbit couplings in the nonadiabatic quantum dynamics with quantum fidelity and with its efficient "on-the-fly" ab initio semiclassical approximation

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