High-temperature superconductor of sodalite-like clathrate hafnium hexahydride.

Hafnium hydrogen compounds have recently become the vibrant materials for structural prediction at high pressure, from their high potential candidate for high-temperature superconductors. In this work, we predict $$\hbox {HfH}_{6}$$ by exploiting the evolutionary searching. A high-pressure phase adopts a sodalite-like clathrate structure, showing the body-centered cubic structure with a space group of $$Im\bar{3}m$$ . The first-principles calculations have been used, including the zero-point energy, to investigate the probable structures up to 600 GPa, and find that the $$Im\bar{3}m$$ structure is thermodynamically and dynamically stable. This remarkable result of the $$Im\bar{3}m$$ structure shows the van Hove singularity at the Fermi level by determining the density of states. We calculate a superconducting transition temperature ( $$T_{c}$$ ) using Allen-Dynes equation and demonstrated that it exhibits superconductivity under high pressure with relatively high- $$T_{c}$$ of 132 K.