Adsorption, Isomerization, and Decomposition of HCN on Si(100)2 × 1: A Computational Study with a Double-Dimer Cluster Model

The adsorption, isomerization, and decomposition of HCN on Si(100)-2 × 1 surface have been investigated by means of a density functional theory calculation using a double-dimer cluster model. The results revealed that both HCN and its HNC isomer can be readily adsorbed on a Si−Si dimer either dissociatively or molecularly in an end-on and a side-on configuration. Side-on adsorption occurs by the cycloaddition of the C⋮N group on to the Si−Si dimer, whereas dissociative adsorption gives rise to H(a) and CN(a) adspecies initially via the end-on configuration on the same dimer or across the two dimers. Adsorbate−adsorbate interactions and reactions have also been studied with two HCN molecules. For the end-on adsorption, the first HCN(a) exerts a significant effect on the adsorption geometry of the second HCN. In particular, a synergetic effect has been observed for the parallel adsorption of two HCNs with their CN groups bridging across the two dimers. For the side-on adsorption, the adsorbate−adsorbate int...