Stabilization mechanism of clathrate H cages in a room-temperature superconductor LaH\(_{10}\)

• Published in: arXiv.org
• Main Authors: Yi, Seho, Wang, Chongze, Jeon, Hyunsoo, Jun-Hyung Cho
• Format: Paper Journal Article
• Language: English
• Published: Ithaca Cornell University Library, arXiv.org 03.07.2020
• Subjects: Atomic properties; Cages; Charge transfer; Clathrates; Electrons; First principles; Hydrides; Lanthanum; Physics - Materials Science; Physics - Superconductivity; Rare earth elements; Room temperature; Superconductivity
• ISSN: 2331-8422
• DOI: 10.48550/arxiv.2007.01531

Lanthanum hydride LaH\(_{10}\) with a sodalitelike clathrate structure was experimentally realized to exhibit a room-temperature superconductivity under megabar pressures. Based on first-principles calculations, we reveal that the metal framework of La atoms has the excess electrons at interstitial regions. Such anionic electrons are easily captured to form a stable clathrate structure of H cages. We thus propose that the charge transfer from La to H atoms is mostly driven by the electride property of the La framework. Further, the interaction between La atoms and H cages induces a delocalization of La-5\(p\) semicore states to hybridize with H-1\(s\) state. Consequently, the bonding nature between La atoms and H cages is characterized as a mixture of ionic and covalent. Our findings demonstrate that anionic and semicore electrons play important roles in stabilizing clathrate H cages in LaH\(_{10}\), which can be broadly applicable to other high-pressure rare-earth hydrides with clathrate structures.