Abstract: In this work, ab initio and DFTcalculations have been performed to investigate the state transitions in photoinduced electron transfer reactions between 9,10-dicyanoanthracene(DCA) and durene(DUR).The face-to-face structure of complex has been optimized by using M＜ller-Plesset method, and the counterpoise method is adopted to consider the basis set superposition error correction of interaction energy.Four low-lying excited singlet states of complex have been investigated by using the method of configuration interaction singles(CIS).It is concluded that the transitions from the S₀state to the S₁and S₂states do not lead to the charge separation.The transition from S₀state to S₃state is found to produce a charge-separated state directly, but the small oscillator strength indicates that the intensity of the charge transfer(CT) absorption is probably quite weak.The decays of charge-separated state to the locally excited states and the ground state have been examined.According to the generalized Mulliken-Hush model, the electronic coupling matrix elements in the charge recombination(CR) processes have been evaluated.Our investigation makes it clear that the direct CT absorption is rather weak, while the CR process from the CTstate to a locally excited state or to the ground state seems possible.

Key words: Ab initio, Electron transfer, Excited state, Electronic coupling matrix element