  We present a new approach based on the static density functional theory (DFT)
to describe paramagentic MnO, which is a representative paramagnetic Mott
insulator. We appended the spin noncollinearity and the canonical ensemble to
the magnetic sampling method (MSM), which is one of the supercell approaches
based on disordered local moment model. The combination of the noncollinear MSM
(NCMSM) with DFT$+U$ represents a highly favorable computational method called
NCMSM$+U$ to accurately determine the paramagnetic properties of MnO with
moderate numerical cost. The effects of electron correlations and spin
noncollinearity on the properties of MnO were also investigated. We revealed
that the spin noncollinearity plays an important role in determining the
detailed electronic profile and precise energetics of paramagnetic MnO. Our
results illustrate that the NCMSM$+U$ approach may be used as an alternative to
the $\textit{ab initio}$ framework of dynamic mean field theory based on DFT in
the simulation of the high-temperature properties of Mott insulators.
