Quasirelativistic Potential Energy Curves of NaRb for Direct Spectra Interpretation

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.