Nature of the Peierls transition in charge density wave systems: Strong coupling versus weak coupling

A brief experimental review of the dynamics of the Peierls transition in quasi-one-dimensional conductors is presented. Softening of a phonon mode is observed in the vicinity of the Peierls transition in platinum chain compounds and blue bronze K0.3MoO3, while no Kohn anomaly is detected in (TaSe4)2I and NbSe3. Neutron scattering and angle resolved photoemission spectroscopy experiments lead us to consider that strong interactions could be generic features of quasi-one-dimensional systems with a charge density wave ground state.