A theoretical study on adsorption geometry of ethylene on the Ni(1 1 0) surface

The favourite adsorption sites of ethylene on the Ni(1 1 0) surface at high and low coverage has been obtained by the cluster calculations. At low coverage, an isolated ethylene molecule occupies a site approximately midway between short-bridge and atop sites, the C-C-axis of molecule is slightly parallel to the ridges and offset in <1 0 0> direction, the tilt angle of the C-C-axis with the Ni surface plane is about 10 degrees. The C-C bond length is 1.51 Angst. At high coverage (0.5 ML), ethylene on Ni(1 1 0) form a c (2x4) ordered phase. The local adsorption sites of two ethylene molecules in a surface unit mesh are found to be similar to that at low coverage, but the C-C bond lengths are 1.42 and 1.43 Angst, respectively