$E\otimes e$ Jahn-Teller Effect in $C_{70}^{3-}$ Systems

TL;DR

This study investigates the electron-phonon interactions in $C_{70}^{3-}$ anions, revealing a Jahn-Teller effect that causes symmetry breaking and lattice distortion, with implications for Berry phase phenomena.

Contribution

The paper demonstrates the Jahn-Teller effect in $C_{70}^{3-}$ and analyzes the contributions of various vibrational modes to the lattice relaxation process.

Findings

Jahn-Teller effect causes symmetry breaking in $C_{70}^{3-}$.

Both Jahn-Teller active and non-active modes influence lattice relaxation.

$C_{70}^{3-}$ is a promising candidate for Berry phase studies.

Abstract

The electron-phonon interaction in $C_{70}$ anions is studied by making use of a lattice relaxation approach. We find there exists a Jahn-Teller effect in $C_{70}^{3-}$ system, due to an extra electron being doped to the double degenerate $E_{1}^{''}$ state. As a result of this effect, the original $D_{5h}$ symmetry of the ground state becomes unstable, which causes distortion of the lattice configuration. The only symmetry maintained in the final state of the relaxation is the $x-y$ plane reflection symmetry. We further find that besides the Jahn-Teller active $A_{1}^{'}, A_{2}^{'}, E_{2}^{'}$ modes, the non-Jahn-Teller active $E_{1}^{'}$ vibrations also contribute to the relaxation process, which come from the nonlinear effect and are two or three orders smaller than those of the Jahn-Teller active modes. We suggest that the $C_{70}^{3-}$ molecule is a promising Berry Phase candidate in this effective $E \otimes e$ Jahn-Teller system.