Undamped low-energy plasmon in AlH3 at high pressure
5 páginas, 5 figuras.-- PACS number(s): 71.45.Gm. Trabajo presentado a "DIPC10 : Passion for Knowledge" celebrado en Donostia (España) del 27 de septiembre al 1 de octubre de 2010. ; Pressure strongly modifies electronic and optical properties of solids. In this work we report ab initio time-dependent density-functional theory calculations of the dielectric response of the high-pressure metallic phase of aluminum hydride (AlH3) within the random-phase approximation. Besides the conventional free-electronlike plasmon, which is highly damped, low-energy transitions between states near the Fermi level that appear in this metallized phase give rise to a low-energy undamped collective mode. This feature is expected to induce an abrupt edge in the experimentally measured reflectivity just below 1 eV and also affect electronic correlations close to the Fermi energy. Our work shows that AlH3 is basically a hydrogen sublattice weakly perturbed by Al atoms. ; This work was partially supported by the University of the Basque Country UPV/EHU and the Basque Government (Grants No. GIC07IT36607 and No. IT-366-07), as well as the Spanish Ministerio de Educación y Ciencia (Grant No. FIS2009-09631). Computing facilities were provided by the SGI/IZO-SGIker UPV/EHU (supported by the National Program for the Promotion of Human Resources within the National Plan of Scientific Research, Development and Innovation-Fondo Social Europeo, MCyT and the Basque Government) and by the Donostia International Physics Center (DIPC) foundation. ; Peer reviewed