Effect of Coulomb interactions on the vibronic couplings in C60(-)

Vibronic couplings in C(60)(-) anion are discussed on the basis of the concept of the vibronic coupling density (VCD) [T. Sato, K. Tokunaga, and K. Tanaka, J. Chem. Phys. 124, 024314 (2006); K. Tokunaga, T. Sato, and K. Tanaka, J. Chem. Phys. 124, 154303 (2006); and T. Sato, K. Tokunaga, and K. Tanaka, J. Phys. Chem. A 112, 758 (2008)]. The VCD analysis clearly reveals that the coupling to the bending h(g)(2) mode is weaker than the coupling to the stretching h(g)(7) and h(g)(8) modes. For the vibronic couplings with the stretching modes, polarizations of the electron density difference on the bonds play a crucial role in the vibronic couplings. Such a polarized electron density difference appears as a result of the Coulomb interactions between the electrons in the lowest unoccupied molecular orbital and relevant doubly-occupied orbitals.