Formation of diphosphorus (P

We estimated radiative association rate coefficients for P(4S) atoms and P+(3P) ions interacting with P(4S) and N(4S) atoms to form P2+ and PN+ cations, respectively. The required potential energy curves of P2+ and PN+ and the transition dipole moments coupling the states of interest were obtained using the multi-reference configuration interaction approach with a Davidson correction (MRCI+Q). The rate coefficients were obtained from the cross-sections, which were computed using a quantum mechanical method. The maximum rate constant values we predict are 3.13×10−19 cm3 s−1 at 10 K for the PN+ cation and 1.66×10−16 cm3 s−1 at 3500→6000 K for the P2+ cation. For the convenience of astrochemical applications, the thermal rate constants were fitted to the standard equation, $\[k(T)=A(\frac{T}{300})^{\alpha} e^{\beta / T}\]$.