Adsorptions of Ni₈ cluster on the regular and defect sites of the MgO(001) surface

The adsorption of Ni₈ clusters on the anionic (Mg ₂₅O₂₄^0/+/2+, F_s^0/+/2+) and cationic (Mg₂₄O₂₅^0/-/2-, V_s ^0/-/2-) vacancies, as well as on the regular sites (Mg ₂₅O₂₅, Mg²⁺ and NiMg₂₄O ₂₅, Ni²⁺) of the MgO(001) surface has been investigated at the PW91/DND level of density functional theory. On the basis of the computed adsorption energies, the metal deposition has the decreasing order of Ni ₈/V_s > Ni₈/V_s^- > Ni₈/V_s^2- > Ni₈/F_s ²⁺ ≈ Ni₈/ Ni²⁺ ≈ Ni₈/F _s⁺ ≈ Ni₈/Mg²⁺ > Ni ₈/F_s, > Ni₈/O^2-. Strong electron and charge transfers are found between Ni₈ cluster and vacancies or regular sites. The electronic property of the vacancies has been analyzed.