Abstract
Density functional theory (DFT) calculations are performed using the full-potential linearized augmented plane wave (FP-LAPW) and generalized gradient approximation (GGA). The present study investigates the energetic, electronic and magnetic properties of the variant terminations of NbRu (001) with and without hydrogen atoms. The effects of Fe or Ni overlayer on the above properties are also investigated. Hydrogen atoms are found to prefer the octahedral sites in the bulk NbRu β-phase system. Absorbed H atoms act as a dilation center and cause a decrease of the cohesive energy of the NbRu β-phase system. Ru/NbRu (001) surface is found most stable and suitable for epitaxial growth deposition. The adsorption of H atoms on Ru/NbRu (001) surface is more energetic than that on Nb/NbRu (001) surface. Ferromagnetic order is found for Fe and Ni atoms in M/Ru/Nb/Ru (001) and M/Nb/Ru/Nb (001) surfaces (M=Fe, Ni). The adsorption of hydrogen is found to be preferable at the hollow fourfold sites on both H/Fe/Ru/Nb/Ru (001) and H/Fe/Nb/Ru/Nb (001) surfaces, while it prefers the bridge site on both H/Ni/Ru/Nb/Ru (001) and H/Ni/Nb/Ru/Nb (001) surfaces. A marked reduction of the local density of states at Fermi level and the magnetic moments of M surface layer is observed due to the presence of hydrogen.
► Absorbed H atoms cause a decrease of the cohesive energy of NbRu β-phase system. ► Ru/NbRu (001) surface is most stable and suitable for epitaxial growth deposition. ► The adsorption of H on Ru/NbRu (001) is more energetic than on Nb/RuNb (001). ► The magnetism of the surface layer covered by H atom is decreased.