Chemical templates that assemble the metal superhydrides

TL;DR

This paper introduces a chemical template perspective to understand the formation and stability of metal superhydrides, explaining their structures and guiding the prediction of new superhydride materials.

Contribution

It proposes a novel chemical template theory based on electron localization and aromatic units, surpassing traditional bond explanations for superhydride stability.

Findings

Metal lattices show electron localization matching H lattice templates.

H lattices are composed of 3D aromatic units stabilized by metal templates.

The theory predicts new superhydride materials, including two-metal variants.

Abstract

The recent discoveries of many metal superhydrides provide a new route to room-temperature superconductors. However, their stability and structure trends and the large chemical driving force needed to dissociate H2 molecules and form H covalent network cannot be explained by direct metal-hydrogen bonds and volume effect. Here, we demonstrate that the understanding of superhydrides formation needs a perspective beyond traditional chemical bond theory. Using high-throughput calculations, we show that, after removing H atoms, the remaining metal lattices exhibit large electron localization at the interstitial regions, which matches excellently to the H lattice like a template. Furthermore, H lattices consist of 3D aromatic building units that are greatly stabilized by chemical templates of metals close to s-d border. The chemical template theory can naturally explain the stability and structure trends of superhydrides and help to predict new materials such as two-metal superhydrides.