TRIPLET-STATE CHARACTERISTICS OF SMALLER FULLERENES

We studied the energetics and the geometry of the distorted triplet st ructures of C-50, C-56 and C-56 theoretically within a simple one-elec tron-per-site model. Excited state wave functions were constrained int o lower symmetries by appropriate group theoretical projection technic s. Jahn-Teller distortions were monitored for degenerate vertical exci tations. The distortion energies are typically a few tens of meV, the largest value (-0.1 eV) was found for the C-2v' (3)A(1) and B-3(1) sta tes of C-50. Zero-field-splittings of various triplets were evaluated; the signs and values of the resulting D and E parameters are quite se nsitive to the system and to the symmetry of the particular excited st ate.