Dissociation of O2 molecule chemisorbed on Si1 − xGex/Si(001)

OO bond breaking in O2 chemisorbed on addimers of perfect Si1 − xGex/Si(001) surface was investigated using ab initio calculations. A hybrid quantum mechanical–molecular mechanical approach (QM/MM) and a CASSCF(2;2)/N21-3** method were employed to simulate this reaction. The ability of such model to reproduce correct results was confirmed by additional calculation of dissociation barrier using different modifications of CASSCF method, basis set and surface clusters. The act of OO bond breaking was found to be energetically favorable only due to local surface stain, with an activation energy of 0.2 eV.