The Configuration and electronic state of SO adsorbed on Au surface

Suzuki, Chikashi ; Nakagiri, Toshio  

We evaluated the adsorption of SO molecule on the Au (111) surface using the first-principles calculations by a slab model with a periodic boundary condition. We find that there are six stable adsorption configurations on the Au surface, where SO molecules are adsorbed above the three-fold fcc and hcp hallow sites and atop site. In two of these configurations, S and two O atoms are bound to the Pt atoms, and in two other of them, all the three O atoms are bound to Pt surface atoms, and then, S atom is bound to Au surface atom on the atop site and O atoms are situated on the hallow sites. In addition, it is found that molecular orbitals of SO and those of Au surface are hybridized in the active metal d-bands region, that the localized molecular orbitals in SO are stabilized, and that the charge is transferred from Au to S 3p by SO adsorption on Au surface though the other interaction of S and O (bound to Au) component with Au is little. In addition, the bond between S and O bound to Au become weak by SO adsorption on Au surface because the charge polarization to O-Au bond weakens the bond between S and O bound to Au. This interaction is assumed to encourage the breakage of S-O bond.