Normal mode analysis for a comparative study of relaxation processes of charge transfer and photoexcitation in C₆₀

In this article we employ a normal mode analysis to the relaxation processes of charge transfer and photoexcitation in $C60$⁠. It is found that only a few $Hg$ modes, the so-called dominant modes, play a critical role in the relaxation, which may imply that only a few $Hg$ modes can have a strong electron–phonon coupling constant. This is consistent with recent experimental results, although previous calculations reported that almost all the $Hg$ modes have roughly the same coupling constant. Those dominant modes control mainly the early and the later behaviors and determine the relaxation times of the processes. The difference between the relaxation times of charge transfer and photoexcitation can also be understood from the dominant modes. We discover that the eigenvectors of the dominant modes are very unique, i.e., if the bond lengths are altered along the eigenvectors, one can observe a change in the lattice by a typical laminar distortion structure.