Vibronic interactions and superconductivity in acene anions and cations

Vibronic interaction and its role in the occurrence of superconductivity in the monoanions and cations of benzene and acenes are studied. The vibratio nal frequencies and the vibronic coupling constants for benzene and acenes are computed and analyzed and electron-phonon coupling constants in the mon oanions and cations are evaluated. The C-C stretching E-2g mode of 1656 cm( -1) affords large electron-phonon coupling constants in the monoanion and c ation of benzene. The C-C stretching A(g) modes of 1400-1600 cm(-1) and the lowest frequency A(g) mode play an important role in the electron-phonon c oupling in the monoanions of acenes, while the only C-C stretching A(g) mod es of 1400-1600 cm(-1) afford large electron-phonon coupling constants in t he monocations of acenes. We estimate possible superconducting transition t emperatures T(c)s for the monoanions and cations of benzene and acenes. The predicted T(c)s for the monocations of benzene and acenes are much lower t han those for the monoanions. Possible high-temperature superconductivity i n the monoanion and cation of benzene is suggested. (C) 2001 American Insti tute of Physics.