We have performed density functional theory calculations for the surface structure of O/Pd(100)-p(2×2), formed by the adsorption of oxygen atoms of 0.25 ML. The oxygen atoms adsorb preferentially at the fourfold hollow site, and the calculated O-Pd bond length is 2.15 Å. The first interlayer spacing (d₁₂) of Pd(100) expands by +0.8% due to the oxygen adsorption, which differs from the experimental value of +3.6% reported by a previous LEED study. Assuming that the LEED sample was possibly contaminated by hydrogen atoms, we also examined the effect of hydrogen impurities on the surface structure. Hydrogen atoms adsorbed on O/Pd(100)-p(2×2) are found to result in large expansions of d₁₂ of Pd(100). Our analysis estimates the amount of hydrogen atoms remaining on the LEED sample as ∼0.3 ML.

Keywords: Pd(100),산소,수소,표면구조,밀도범함수이론,Oxygen,Hydrogen,Surface structure,Density functional theory