title: Franck-Condon factors perturbed by damped harmonic oscillators: solvent enhanced X (1)Ag ↔ A(1)B1u absorption and fluorescence spectra of perylene.
abstract: Damped harmonic oscillators are utilized to calculate Franck-Condon factors within displaced harmonic oscillator approximation. This is practically done by scaling unperturbed Hessian matrix that represents local modes of force constants for molecule in gaseous phase, and then by diagonalizing perturbed Hessian matrix it results in direct modification of Huang-Rhys factors which represent normal modes of solute molecule perturbed by solvent environment. Scaling parameters are empirically introduced for simulating absorption and fluorescence spectra of an isolated solute molecule in solution. The present method is especially useful for simulating vibronic spectra of polycyclic aromatic hydrocarbon molecules in which hydrogen atom vibrations in solution can be scaled equally, namely the same scaling factor being applied to all hydrogen atoms in polycyclic aromatic hydrocarbons. The present method is demonstrated in simulating solvent enhanced X (1)Ag ↔ A(1)B1u absorption and fluorescence spectra of perylene (medium-sized polycyclic aromatic hydrocarbon) in benzene solution. It is found that one of six active normal modes v10 is actually responsible to the solvent enhancement of spectra observed in experiment. Simulations from all functionals (TD) B3LYP, (TD) B3LYP35, (TD) B3LYP50, and (TD) B3LYP100 draw the same conclusion. Hence, the present method is able to adequately reproduce experimental absorption and fluorescence spectra in both gas and solution phases.
authors.affiliation: Institute of Molecular Science, Department of Applied Chemistry and Center for Interdisciplinary Molecular Science, National Chiao-Tung University, Hsinchu 30050, Taiwan.
authors.forename: Chen-Wen
authors.initials: CW
authors.lastname: Wang
authors.affiliation: Institute of Molecular Science, Department of Applied Chemistry and Center for Interdisciplinary Molecular Science, National Chiao-Tung University, Hsinchu 30050, Taiwan.
authors.forename: Ling
authors.initials: L
authors.lastname: Yang
authors.affiliation: Institute of Molecular Science, Department of Applied Chemistry and Center for Interdisciplinary Molecular Science, National Chiao-Tung University, Hsinchu 30050, Taiwan.
authors.forename: Chaoyuan
authors.initials: C
authors.lastname: Zhu
authors.affiliation: Department of Chemistry, Beijing Normal University, Beijing 100875, People's Republic of China.
authors.forename: Jian-Guo
authors.initials: JG
authors.lastname: Yu
authors.affiliation: Institute of Molecular Science, Department of Applied Chemistry and Center for Interdisciplinary Molecular Science, National Chiao-Tung University, Hsinchu 30050, Taiwan.
authors.forename: Sheng-Hsien
authors.initials: SH
authors.lastname: Lin