  In spite of extensive studies on NiO and their accomplishments, the rich
physics still raises unsolved physical problems. In particular, the nature of
the two-peak structure in the valence band photoemission spectra is still
controversial. By using \textit{ab initio} LQSGW+DMFT, the two-peak structure
is shown to be driven by the concerted effect of antiferromagnetic ordering and
intersite electron hopping. Magnetic ordering in the Ni-$e_{g}$ orbitals splits
majority- and minority-spin Ni-$t_{2g}$ levels due to local Hund's coupling.
Strong hybridization between O-$p$ and Ni-$e_g$, a signature of the Zhang-Rice
bound state formation, boosts oxygen-mediated intersite Ni-$e_g$ orbital
hopping, resulting in the enhancement of majority-spin Ni $t_{2g}$-$e_{g}$
splitting. Interestingly, these two splittings of distinct physical origins
match and give rise to the observed two-peak structure in NiO. Our new
understanding should be useful in designing advanced devices based on the NiO
for the hole transport.
