Jahn-Teller effect in the cubic fullerides A3C60

Compared to isolated C$_{60}^{3-}$ ions, characterized by a threedimensional equipotential trough at the bottom of lowest adiabatic potential energy surface (APES), Jahn-Teller (JT) effect in cubic fullerides is additionally influenced interaction JT distortions C$_{60}$ sites with vibrational modes lattice. This leads modification stabilization and warping each fullerene site, as well different sites. Here we investigate these effects three fcc A=K,Rb,Cs Cs$_3$C$_{60}$ bcc (A15) structure. DFT calculations orbital vibronic coupling constants phonon spectra have been done for fully ordered lattices (1 C$_{60}$/u.c.). Based on them elastic response function local has evaluated APES investigated. To this end an expression latter coordinates all derived. The results show that slightly increases compared few meV occurs. nearest- next-nearest-neighbor similar order magnitude. These arise first due displacements neighbor alkali atoms are more pronounced than A15 compound. study support picture weakly hindered independent rotations deformations A$_3$C$_{60}$.