Identification of Phason Anomalies in the Low-Temperature Specific Heat of the Alkali Metals

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Abstract
The low-temperature lattice specific heats of K, Rb, and Cs in a model in which a normal ground state is assumed have been evaluated. In comparing our results with experiment, no evidence has been seen that any of these materials have charge-density-wave ground states. It is argued that the apparent anomaly in Rb, identified by Giuliani and Overhauser and ascribed by them to phason excitations of a charge-density-wave ground state, reflects the dispersion of low-energy transverse-phonon modes.