Rotational excitation of the interstellar NH₂ radical by H₂

We present quantum close-coupling calculations for the rotational excitation of the interstellar amidogen radical NH₂ due to collisions with H₂ molecules. The calculations are based on a recent, high-accuracy full-dimensional NH₄ potential energy surface adapted for rigid-rotor scattering calculations. The collisional cross section calculations are performed for all transitions among the first 15 energy levels of both ortho- and para-NH₂ and for total energies up to 1500 cm^-1. Both para- and ortho-H₂ colliding partners are considered. The cross sections for collision with para- and ortho-H₂ are found to differ significantly, the magnitude of the ortho-H₂ ones being dominant. No strong propensity rules are observed but transitions with Δk_c=0 are slightly favored.