Indium atoms were found to interact strongly with the so-called C defects, commonly present on the Si(100)-2x1 surface. As a consequence, In rows growing on the surface were pinned to these defects. The reaction of adsorbate with the C defects was studied in detail by ab initio calculations in combination with the scanning tunnelling microscopy and spectroscopy. For calculations, a model of the C defect as being a dissociated water molecule was successfully adopted. The presence of the defect induced a surface state just below the Fermi level, resulting in a surface-mediated reaction forming a row of In atoms. The end of the row not pinned to a C defect was unstable at room temperature. A transition between metallic and non-metallic characters of the unpinned termination, given by parity of atoms in the row, was observed and explained by ab initio calculations.Defects on the Si(100)-(2x1) Surface - Anchoring Sites of the Surface Polymerization Reaction of In Atoms. P.Kocán, L.Jurczyszyn, P.Sobotík, I.Oštádal: Physical Review B, 2008, 77[11], 113301 (4pp)