The thermal expansion at constant pressure of solid CD$_4$ III is calculated for the low temperature region where only the rotational tunneling modes are essential and the effect of phonons and librons can be neglected. It is found that in mK region there is a giant peak of the negative thermal expansion. The height of this peak is comparable or even exceeds the thermal expansion of solid N$_2$, CO, O$_2$ or CH$_4$ in their triple points. It is shown that like in the case of light methane, the effect of pressure is quite unusual: as evidenced from the pressure dependence of the thermodynamic Gruneisen parameter (which is negative and large in the absolute value), solid CD$_4$ becomes increasingly quantum with rising pressure.

中文翻译：

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固体氘代甲烷中的负热膨胀

固体CD$_4$III在恒压下的热膨胀是针对低温区域计算的，该区域只有旋转隧穿模式是必不可少的，声子和libron的影响可以忽略不计。发现在mK区存在负热膨胀的巨峰。该峰的高度与固体 N$_2$、CO、O$_2$ 或 CH$_4$ 在其三相点的热膨胀相当甚至超过。结果表明，在轻质甲烷的情况下，压力的影响是非常不寻常的：从热力学 Gruneisen 参数（它是负的且绝对值很大）的压力依赖性证明，固体 CD$_4$ 变得越来越大量子与上升的压力。