Theory of transverse phasons in potassium

Abstract

A quantitative theory of the frequency dispersion relation for long-wavelength, transverse phasons of a charge-density-wave state is developed. The emphasis is directed toward alkali metals and in particular potassium. For these the theory is parameter free. The transversephason velocity is found to be of the same order of magnitude as the sound velocity. Also, the electric field that would arise from the charge modulation of the conduction electrons is almost completely screened by sinusoidal displacements of the positive ions. The relevance of these results to observable phenomena is discussed.