1998/07/04 by Kwai-Kong Ng, K. K. Ng, F. C. Zhang +4 · 92 citations
Chemistry · Physics and Astronomy · #Advanced Chemical Physics Studies #Atomic physics #Band gap #Chemistry #Condensed matter physics #Electron #Electronic structure #Hydride #Hydrogen #Inorganic chemistry #Ion #Lanthanum #Materials science #Metal #Physics #Quantum mechanics #Quantum, superfluid, helium dynamics #Rare-earth and actinide compounds #Vacancy defect #Yttrium #cond-mat.mtrl-sci #cond-mat.str-el
paper · pdf · doi:10.1103/physrevb.59.5398
published in Physical review. B, Condensed matter 59(8), 5398-5413 (American Physical Society) · 18 pages, 16 figures and 6 tables. Submitted to PRB
arxiv created 1998/07/04 · openalex publication_date 1999/02/15 · arxiv updated 2009/11/30 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
Recently it has been discovered that lanthanum, yttrium, and other metal hydride films show dramatic changes in the optical properties at the metal-insulator transition. Such changes on a high-energy scale suggest the electronic structure is best described by a local model based on negatively charged hydrogen (H^\ensuremath-) ions. We develop a many-body theory for the strong correlation in a H^\ensuremath- ion lattice. The metal hydride is described by a large U limit of an Anderson lattice model. We use lanthanum hydride as a prototype of these compounds, and find that LaH3 is an insulator with a substantial gap consistent with experiments. It may be viewed either as a Kondo insulator or a band insulator due to strong electron correlation. A H vacancy state in LaH3 is found to be highly localized due to the strong bonding between the electron orbitals of hydrogen and metal atoms. Unlike the impurity states in the usual semiconductors, there is only weak internal optical transitions within the vacancy. The metal-insulator transition takes place in a band of these vacancy states.