Rotational excitation of HCO+ by collisions with H2

An ab initio potential surface was obtained for the HCO+–H2 interaction, making use of CI for part of the surface. This was then used to compute collisional cross-sections and rate coefficients for a range of temperatures (0–30 K) and between all rotational levels up to and including j = 4. Only collisions with para-H2 were studied here. The effects of different sets of rate coefficients on predicted spectral line intensities were examined.