Formation of a missing row reconstruction on a Cu(100) surface: An atom scale density functional theory based study

The oxygen-induced reconstruction of Cu(100) surfaces has been studied in great detail. Experimentally, missing row reconstruction occurs with an O coverage of 0.5 monolayer (ML). Several DFT-based calculations of vacancy-surface Cu pairs were performed at O coverage between 0 and 0.5 ML. No structure was identified in these calculations as being energetically favoured over the ideal Cu(100) structure. When a Cu atom (0.125 ML) was added to the system, a new energetically favourable missing row and added Cu-O-Cu row structure was found. It has been suggested that this structure is an important intermediate step towards the missing row formation. The transition from the missing and added row structure to the (2√2 × √2)R45o-O reconstruction has the energetic requirement of very good binding sites for the Cu atoms, which can be found on the step boundaries. These results are in excellent agreement with the step edge growth and the formation of strongly anisotropic islands observed by Lahtonen et al. (J. Chem. Phys. 129 (2008) 124703).