Thermal lattice fluctuations in (TaSe4)2l

We report on the optical evidence of thermal lattice fluctuation effects in the charge-density-wave (CDW) compound (TaSe4)2l. We found important deviations from the expected behaviour within a static distorted lattice approach. Our results are in agreement with a recent theoretical model where both the effects of the zero point lattice motions and of the phonon modes coupled to the CDW condensate are taken into account.