Anion Ordering and Atomic Vibrations in (TMTSF)2ClO4

Abstract
We report the first observation of the specific heat anomaly associated with anion ordering in (TMTSF)2ClO4. The phase transition analyse reveals a configuration entropy R Log (2) which can be reduced by 20% on fast cooled sample. The low temperature lattice specific-heat deviate strongly from the prediction of a 3D debye model.