| Abstract
| - By performing ab inito calculations for the TCNE−HMBcomplex, we obtain the optimized geometry andthe vibrational modes of the ground state. We find that symmetryis broken due to a formation of hydrogenbond between one of the hydrogen atoms of HMB and one of the nitrogenatoms of TCNE. We also findthat all the donor−acceptor intermolecular modes are found in thefrequency region less than 100 cm-1.Weidentify donor−acceptor stretching mode at 59cm-1 and two TCNE vibrations at 167 and 170cm-1, whichtwo modes are highly associated with the experimentally observed mode.Deuteriation effects are alsoinvestigated for this complex. We set up a new model for opticaltransitions, which consists of the two CTstates and one ground state including 33 vibrational modes. On thebasis of this new model, we analyze thesteady state absorption and fluorescence spectra to tentatively obtainpotential parameters. We find that theratio of the transition moment of the CT2 state to that of the CT1 isabout 0.3.
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