The top and side views of the NO molecules adsorbed at [(a1) and (a2)] fcc hollow and [(b1) and (b2)] atop sites of the Au(111) surface at a coverage of 0.25 ML. The big yellow, medium red, and small blue spheres represent gold, oxygen, and nitrogen atoms, respectively. The black dashed lines show the supercell used in the calculations.
Schematic drawing of the proposed structure model for NO on O/Au(111): (a) 0.3 ML oxygen covered -O/Au(111) with O adatoms occupying the fcc hollow site. The four sites for NO approaching the surface: (1) atop-O, (2) atop-Au, (3) second neighbor fcc site, and (4) second neighbor hcp site. (b) 1.0 ML oxygen covered -O/Au(111). The three sites for NO approaching the surface: (1) atop-O, (2) Hcp hollow, and (3) atop-Au. The small blue, medium red, and big yellow spheres represent NO molecules, O atoms, and gold atoms, respectively.
(a) Optimized geometry of the molecules adsorbed on the Au(111) surface at a coverage of 0.33 ML defined as . (b) Optimized geometry of adsorbed on Au(111) surface. The medium red, small blue, and big yellow spheres represent oxygen, nitrogen, and gold atoms, respectively. (a) The black dashed lines indicate the and (b) unit cells.
The adsorption energy (defined as ) calculated with a -point sampling for NO adsorption at different sites on clean Au(111) surface with different numbers of gold layers.
The adsorption energy (defined as ) and geometrical parameters for NO adsorption at different sites on clean Au(111) surface. is the angle between N–O molecular axis and the normal of the surface. The vibrational frequency of the gas-phase NO is also listed.
Atomic oxygen adsorption energy (defined as ) and layer distance between O and first Au layer with O on the most stable fcc site.
The vibrational frequencies (in ) of chemisorbed in supercell.
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