AbstractResults of cluster‐Bethe‐lattice calculations for complexes of Si—Si bonds in a‐SiO2 are presented. The influence of such Si04(ySi, [4 − y]O) defects on the local electronic density of states (LDOS) of SiO2 is discussed. For all values of y = 1, 2, 3, 4 localized occupied and empty defect states are found in the SiO2 gap. From cluster calculations using a bond‐orbital representation the defect functions are calculated. The local gap of these defects is distinctly changed only for y = 1, reflecting the x dependence of the SiOx gap for higher x values.