  We report the quasirelativistic potential energy curves including spin-orbit
and scalar-relativistic effects of the NaRb molecule. The calculated curves of
the 0$^+$, 0$^-$, 1, and 2 molecular states correlate for large internuclear
separation with the five lowest atomic energies covering the first P doublet
states of the rubidium and sodium atoms. Several new features of potential
curves are found. Some disagreements with the other theoretical data are found
and discussed. We advocate that our results may be used in the direct way,
skipping the unperturbation of the spin-orbit interaction, for assigning the
molecular spectra.
