First-principles study on the structural and electronic properties of metallic HfH(2) under pressure

The crystal structures and properties of hafnium hydride under pressure are explored using the first-principles calculations based on density function theory. The material undergoes pressure-induced structural phase transition I4/mmm→Cmma→P2(1)/m at 180 and 250 GPa, respectively, and all of these structures are metallic. The superconducting critical temperature T(c) values of I4/mmm, Cmma, and P2(1)/m are 47–193 mK, 5.99–8.16 K and 10.62–12.8 K at 1 atm, 180 and 260 GPa, respectively. Furthermore, the bonding nature of HfH(2) is investigated with the help of the electron localization function, the difference charge density and Bader charge analyses, which show that HfH(2) is classified as a ionic crystal with the charges transferring from Hf atom to H.