# On the possibility of metastable metallic hydrogen

## TL;DR

This paper investigates whether metallic hydrogen can exist in a metastable state at lower pressures using first-principles simulations, finding it likely not to be stable at ambient conditions, which impacts its practical applications.

## Contribution

It provides the first computational evidence on the metastability of metallic hydrogen at lower pressures, addressing a key question for its practical use.

## Key findings

- Metallic hydrogen is metastable at high pressures.
- It is unlikely to be metastable at ambient conditions.
- Implications for fundamental physics and applications are discussed.

## Abstract

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.