Vibronic coupling in C₆₀^- anion revisited: Precise derivations from photoelectron spectra and DFT calculations

The vibronic coupling constants of C$_{60}^-$ are derived from the photoelectron spectrum measured by Wang {\it et al}. [X. B. Wang, H. K. Woo, and L. S. Wang, J. Chem. Phys., {\bf 123}, 051106 (2005).] at low temperature with high-resolutions. We find that the couplings of the Jahn-Teller modes of C$_{60}^-$ are weaker than the couplings reported by Gunnarsson {\it et al}. [O. Gunnarsson, H. Handschuh, P. S. Bechthold, B. Kessler, G. Gantef{\"{o}}r, and W. Eberhardt, Phys. Rev. Lett., {\bf 74}, 1875 (1995).]. The total stabilization energy after $h_g$ and $a_g$ modes is reduced with respect to the previous derivation of Gunnarsson {\it et al}. by 30 \%. The computed vibronic coupling constants using DFT with B3LYP functional agree well with the new experimental constants, so the discrepancy between theory and experiment persistent in the previous studies is basically solved.