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In the present investigation, we report new analytical potential energy curves (APECs) for three triplet electronic states X 3 Σ - , B 3 Σ - , and C 3 Π of sulfur monoxide. For such, ab initio electronic energies have been calculated employing the highly accurate multireference configuration interaction method with Davidson modification associated with aug-cc-pV(5+d)Z basis set. The novel analytical representations have been constructed by fitting such accurate energies utilizing a least-squares fitting procedure. By considering our APECs, molecular properties as spectroscopic parameters, rovibrational levels, and classical turning points were derived. Our results show good agreement when compared with available experimental and theoretical data. The vibronic (vibration–electronic) transition parameters like Franck–Condon factors, Einstein coefficients, transition dipole moment, and r-centroids for the B 3 Σ - - X 3 Σ - band system were also examined. The present findings provide a reliable theoretical reference that could be employed in interpretations of astrochemical and astrophysical observations. Based on the results, we recommend these functional forms to represent the two-body fragments within the double many-body expansion method to develop potential energy surfaces for larger S-bearing species. [ABSTRACT FROM AUTHOR]

• Spectroscopic properties for five low-lying electronic states of N 2 are obtained using ab initio based analitical potential energy curves. • Franck-Condon factors, r-centroids, Einstein coefficients and radiative lifetimes for the second positive ((C 3 Π u − B 3 Π g)) and Herman infrared (C ″ 5 Π u − A ′ 5 Σ g +) bands are reported. • Perturbations in the spectrum of the second positive system can be attributed to N 2 (C″5Π u and N 2 A ′ 5 Σ g + state. We present a detailed investigation about the vibronic (vibration-electronic) transition parameters as Franck-Condon (FC) factors, r-centroids, Einstein coefficients, and radiative lifetimes for some bands of the second positive (C 3 Π u − B 3 Π g) and Herman infrared (C ″ 5 Π u − A ′ 5 Σ g +) band systems of N 2. For such, novel and accurate functional forms are reported. To achieve our goals, ab initio electronic energies have been obtained employing the highly accurate multireference configuration interaction (MRCI) method with Davidson modification associated with aug-cc-pVXZ (X = 5,6) basis set. The present analytical representations were 'constructed by fitting such accurate energies utilizing a least-squares fitting procedure. By considering our Analytical Potential Energy Curves (APECs), we derived molecular properties as spectroscopic parameters, rovibrational levels, and classical turning points. Our results are compared with available experimental and theoretical data. In addition, we demonstrate that observed perturbations in the experimental spectrum of the second positive system can be also attributed to N 2 (C″5Π u) and N 2 (A ′ 5 Σ g +). Other important effects of these perturbations are presented. [ABSTRACT FROM AUTHOR]