Low- and high-temperature anomalies in the physical properties of solid methane

Near 20.48K and in the temperature range 60–70K, anomalous behavior of thermodynamic, spectral, plastic, elastic and other properties of solid methane is observed. The anomalies in the vicinity of 20.48K are due to the phase $\alpha -\beta$ transition. Anomalies in a relatively wide range of 60–70K are shown to be related to the essentially quantum nature of the collective rotation of methane molecules. The provided analysis of the high-temperature anomalies encompasses a more extensive set of phenomena in comparison with the low-temperature ones. Key words: solid methane, anomalies of physical properties, phase transition, rotational temperature, quantum-classical transition.