Cⁿ₇₈ were studied systematically bythe INDO (Intermediate neglect differential overlap) method. It was indicated that C_2v isomer of C₇₈is more stable than C_2v′. In Cⁿ₇₈ (C_2v, C_2v′), Jahn-Teller distortion did not happen. Total energy of Cⁿ₇₈ israised by the increasing in absolute values of electric charge numbers. Based onthe optimized geometries, the electronic spectra of Cⁿ₇₈ were calculated for the first time, electronic transition was assigned theoretically, andthe reason of the red-shift of UV bands for Cⁿ₇₈ compared with that of C₇₈ was discussed.

Key words: C₇₈, Cⁿ₇₈, electronic spectra, INDO