First-principles calculation of LaNi5 surface

Abstract

The spin-polarized, all-electron, ab initio calculations have been performed for the electronic structure of the surface of crystal LaNi5 using the self-consistent cluster-embedding (SCCE) calculation method. The geometrical surface structure of crystal LaNi5 and its electronic structure having the lowest ground-state energy are obtained, with the full relaxation of atomic positions along the direction perpendicular to the surface. On the surface of crystal LaNi5, the La atom protruded, and the Ni atoms caved in, so the surface becomes uneven which increases the contacting area. The effective volume of the surface layer rises by 9%. The Fermi level of the LaNi5 surface, which is contributed by mainly Ni 3d electrons, is much higher than that of body LaNi5. The valence band is not fully filled. For the first two layers of LaNi5 surface, there are 1.15 electrons transferred from La to Ni, and the two layers have small opposite spin magnetic moments which shows the paramagnet. All calculated results show that the properties of LaNi5 surface are significantly different from that of body LaNi5, but very similar to that of hydride LaNi5H7. So the geometrical surface structure of crystal LaNi5 is in favor of the absorption of hydrogen.