that for mono-vacancy (see, Table \[table1\]), is suggested [@kiyl11] to be more stable, [*5-8-5*]{} DV is responsible for migration of DV. [*Ab-initio*]{} calculations in [@kiyl11] show that subsequent transformations of [*555-777*]{} DV into [*5-8-5*]{} then [*5-7-7-5*]{} and again [*5-8-5*]{} DV create finally [*555-777*]{} DV, which differs from the initial one by rotation. [*5-8-5*]{} DV transforms to two sequential [*5-7-7-5*]{} metastable DV structures, which differ each other by rotation of heptagons and shifting of pentagons. The metastable [*5-7-7-5*]{} DV structure finally turns to stable [*5-8-5*]{} DV, the position of which differs slightly from the position of initial [*5-8-5*]{} DV.

In order to see clearly the differences between a divacancy and other possible two-vacancy structures the latter are created, as it is seen from Fig. \[Vac2\], in four different positions within the supercell, belonging both to the same or to different sublattices. Note that study of two-vacancies problem is instructive one in order to understand Lieb’s rule and contribution of the dangling bonds to the magnetization.

Two removal vacancies’ positions in the supercell is depicted in Fig. \[Vac2\]a, where the vacancies at ’even distance’ and the reference vacancy, showing by red, belong to the same sublattice (see, Figs. \[Vac2\]b and $d$), instead 