  Electronic structure of NdNiO3 and YNiO3 are calculated by using LSDA+U
method with rotational invariance. No orbital order on Ni sites is observed in
both systems but different charge orderings. In a small distorting system
NdNiO3, all Ni ions are trivalent and oxygen sites have a particular ordering,
both in charge and orbital. In a large distorting system YNiO3, the charge
disproportionation occurs. The charge ordering stabilizes the asymmetry of the
arrangement of the local magnetic moments around each nickel site without the
Jahn-Teller distortion in both systems. The charge compensation occurs in the
local projected density of states, which are discussed in details.
