Vibronic interactions in the positively charged π-conjugated hydrocarbons

Electron-phonon interactions in the monocations of triphenylene and coronene are discussed. The total electron-phonon coupling constants for the monocations (lHOMO) of triphenylene and coronene are estimated to be 0.138 and 0.110 eV, respectively. The lHOMO values for benzene and tetracene were estimated to be 0.244 and 0.107 eV, respectively. Therefore, the molecular structures as well as the molecular sizes are closely related to the strengths of the electron-phonon interactions. The reason for the calculated results is discussed in detail in terms of the phase patterns of the highest occupied molecular orbitals (HOMO). The condition under which two electron pairing and the Bose-Einstein condensation are realized is also discussed.