Journal of Physical Chemistry A, Vol.110, No.44, 12213-12221, 2006
DFT and TDDFT study related to electron transfer in nonbonded porphine center dot center dot center dot C-60 complexes
Spectroscopic properties of a ground state nonbonded porphine-buckminsterfullerene (H2P center dot center dot center dot C-60) complex are studied in several different relative orientations of C-60 with respect to the porphine plane by using the density functional (DFT) and time-dependent density functional (TDDFT) theories. The geometries and electronic structures of the ground states are optimized with the B3LYP and PBE functionals and a SVP basis set. Excitation energies and oscillator strengths are obtained from the TDDFT calculations. The relative orientation of C-60 is found to affect the equilibrium distance between H2P and C-60 especially in the case of the PBE functional. The excitation energies of different H2P center dot center dot center dot C-60 complexes are found to be practically the same for the same excitations when the B3LYP functional is used but to differ notably when PBE is used in calculations. Existence of the states related to a photoinduced electron transfer within a porphyrin-fullerene dyad is also studied. All calculations predict a formation of an excited charge-transfer complex state, a locally excited donor (porphine) state, as well as a locally excited acceptor (fullerene) state in the investigated H2P center dot center dot center dot C-60 complexes.