The origin of the site preference of H adsorption on Pd(100)

Spin-polarized density functional theory （DPT） calculations are carried out to determine the site preference of H adsorption on Pd（100） surface and subsurface, We carefully scrutinize the energy difference between different patterns at θ=0.50 ML and confirm the LEED observation that surface adsorption can form c（2×2） ordering structure. On the contrary, we disclose that p（2×1） structure become more favorable than c（2×2） for subsurface adsorption. These site preferences are rationalized via an analysis of the layer and orbital resolved density of states. Furthermore, we propose that the interstitial charge as a key factor determining the preferred H adsorbed site.

Spin-polarized density functional theory(DFT)calculations are carried out to determine the site preference of H adsorption on Pd(100)surface and subsurface.We carefully scrutinize the energy difference between different patterns at=0.50 ML and confirm the LEED observation that surface adsorption can form c(2×2)ordering structure.On the contrary,we disclose that p(2×1)structure become more favorable than c(2×2)for subsurface adsorption.These site preferences are rationalized via an analysis of the layer and orbital resolved density of states.Furthermore,we propose that the interstitial charge as a key factor determining the preferred H adsorbed site.