On the possibility of metastable metallic hydrogen

Metallic hydrogen is expected to exhibit remarkable physics. Examples include high-temperature superconductivity and possible novel types of quantum fluids. These could have revolutionary practical applications. The pressures required to obtain metallic hydrogen, however, are expected to be significant. For practical, and terrestrial applications, a key question is therefore whether this phase is metastable at lower pressures. In this work, this possibility is investigated, using first-principles simulations. The results show that metallic hydrogen is metastable, but strongly suggest that it is not so to ambient conditions. Implications of these results for fundamental physics, and also practical applications of metastable metallic hydrogen are discussed.