"Ultrafast excited state proton transfer of 2-(2'-hydroxyphenyl)benzothiazole: Theoretical analysis of the skeletal deformations and the active vibrational modes"R. de Vivie-Riedle, V. De Waele, L. Kurtz, and E. Riedle
J. Phys. Chem. A 107, 10591 - 10599 (2003)
The involvement of skeletal deformations in the ultrafast excited state proton transfer of 2-(2’-hydroxyphenyl)benzothiazole (HBT) and the identification of the vibrational modes active in the process are reported. A multidimensional ab initio calculation of ground and excited states at the HF/DFT and CIS/TDDFT level renders the relevant portions of the potential energy surfaces around the minimum energy path connecting the enol and the keto configuration. The frequencies and potential energy distributions of the normal modes and the corresponding deformations of the molecule are calculated for all minimum energy geometries. Along the minimum energy path the nuclear deformation is projected onto the relevant normal modes. This normal mode analysis shows that mainly five low frequency in-plane vibrations are associated with the electronic rearrangement and the transfer of the proton. The theoretical findings are in quantitative agreement with the experimental study presented in the accompanying paper.
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