2017MNRAS.472.2919N

Calculation of the collisional rate coefficients with the most abundant species has been motivated by the desire to interpret observations of molecules in the interstellar medium. This paper will be concerned with rotational excitation of the phosphorus nitride (PN) molecule in its ground vibrational state by collisions with para-H₂(j = 0). Ab intio potential energy surface for the PN-H₂ van der Waals system, considering both molecules as rigid rotors, was computed via CCSD(T) method using the aug-cc-pVTZ basis sets, augmented by a bond functions placed at midway between the PN and H₂ centres of mass. Cross-sections among the 40 first rotational levels of PN in collisions with para-H₂(j = 0) were obtained using close coupling and coupled states calculations, for total energies up to 3000 cm^- 1^. Rate coefficients are presented for temperatures ranging from 5 to 300 K. A strong propensity favouring even Δj transitions is found. The comparison of the new PN-H₂ rate coefficients with previously calculated PN-He rate coefficients shows that significant differences exist.