| Summary: | 博士 === 國立清華大學 === 化學系 === 98 === The electronic coupling values for photo-induced electron transfer (ET) were calculated by the fragment charge difference (FCD) [A. A. Voityuk and N. J. Rösch, Chem. Phys. 117, 5607 (2002)] and the generalized Mulliken-Hush (GMH) schemes [R. J. Cave and M. D. Newton, Chem. Phys. Lett. 249, 15 (1996), R. J. Cave and M. D. Newton, J. Chem. Phys. 106, 9213 (1997)]. We tested several molecules with several different aromatic donors and acceptor combinations, and found that the lowest two local excited (LE) states of each molecule are very different in their ET rates due to their symmetries. We found that the FCD is less prone to problems commonly seen in the GMH scheme especially when the coupling values are small. For a 3-state case where the charge transfer (CT) state is coupled with two different locally excited (LE) states, we propose to follow the 3-state approach for the GMH scheme [M. Rust, J. Lappe, and R. J. Cave, J. Phys. Chem. A 106, 3930 (2002)], and found that it works well with the FCD scheme. A simplified direct diagonalization based on the Rust’s 3-state scheme was also proposed and tested. The overall electron transfer (ET) coupling rates were also calculated and compared to experimental results. We also used several rigid, polycyclic DBA molecules to test for the vibronic effect on the electronic coupling of a rigid donor-bridge-acceptor molecule by Medvedev and Stuchebrukhov’s expression [E. S. Medvedev and A. A. Stuchebrukhov, J. Chem. Phys. 107, 3821 (1997)]. The vibronic effect offers an averaged ET coupling value that is consistent to the observed ET rate in the symmetry forbidden case.
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