Neutron inelastic scattering and X-ray structural study of the charge-density-wave state in K_0.3MoO₃

The Peierls transition in the quasi-one-dimensional conductor K_0.3MoO₃ has been studied to clarify its dynamical nature and the electron correlation problem. A giant Kohn anomaly and the central peak in S(q, omega ) were observed. The amplitude below the transition temperature T_c was also measured. An asymmetry of the elastic diffuse scattering above T_c around the reciprocal point which corresponds to the superlattice point can be explained by taking into account the structure factor of the charge-density wave. A detailed type of modulation of Mo atoms is presented by the X-ray study. No evidence for the correlation effect was observed and the transition of K_0.3MoO₃ seems to be explained by a simple band picture.