  Carbon tetrachloride (CCl$_4$) is one of the simplest compounds having a
translationally stable monoclinic phase while exhibiting a rich rotational
dynamics below 226 K. Recent nuclear quadrupolar resonance (NQR) experiments
revealed that the dynamics of CCl$_4$ is similar to that of the other members
of the isostructural series CBr$_{n}$Cl$_{4-n}$, suggesting that the universal
relaxation features of canonical glasses such as $\alpha$- and
$\beta$-relaxation are also present in non-glass formers. Using molecular
dynamics (MD) simulations we studied the rotational dynamics in the monoclinic
phase of CCl$_4$. The molecules undergo $C3$ type jump-like rotations around
each one of the four C-Cl bonds. The rotational dynamics is very well described
with a master equation using as the only input the rotational rates measured
from the simulated trajectories. It is found that the heterogeneous dynamics
emerges from faster and slower modes associated with different rotational axes,
which have fixed orientations relative to the crystal and are distributed among
the four non-equivalent molecules of the unit cell.

Chemical Physics