title: Low-energy dielectric screening in Pd and PdHx systems.
abstract: Modifications in dielectric properties of palladium upon absorption of hydrogen are investigated theoretically in the low-energy (0-2 eV) region. The calculations were performed with full inclusion of the electronic band structure obtained within a self-consistent pseudopotential approach. In particular, we trace the evolution of the acoustic-like plasmon (AP) found previously in clean Pd with increasing hydrogen concentration. It exists in PdHx up to the hydrogen content x corresponding to the complete filling of the 4d Pd-derived energy bands because of the presence of two kinds of carriers at the Fermi surface. At higher H concentration the AP disappears since only one kind of carrier within the sp-like energy band exists at the Fermi level. Additionally, we investigate the spatial distribution inside the crystal of a potential caused by a time-dependent external perturbation and observe drastic modifications in the screening properties in the PdHx systems with energy and with hydrogen concentration.
authors.affiliation: Departamento de Física de Materiales and Centro Mixto CSIC-UPV/EHU, Facultad de Ciencias Químicas, Universidad del País Vasco, Apdo. 1072, 20080 San Sebastián, Basque Country, Spain. Donostia International Physics Center (DIPC), P. de Manuel Lardizabal, 4, 20018 San Sebastián, Basque Country, Spain. IKERBASQUE, Basque Foundation for Science, Bilbao 48011, Spain.
authors.forename: V M
authors.initials: VM
authors.lastname: Silkin
authors.forename: V U
authors.initials: VU
authors.lastname: Nazarov
authors.forename: I P
authors.initials: IP
authors.lastname: Chernov
authors.forename: I Yu
authors.initials: IY
authors.lastname: Sklyadneva
authors.forename: E V
authors.initials: EV
authors.lastname: Chulkov