Rotational excitation of fulminic acid (HCNO) in collisions with molecular hydrogen

Integral cross sections and rate coefficients for the rotational excitation of fulminic acid (HCNO) induced by collisions with molecular hydrogen are reported in this work. These quantities were derived through quantum time independent close coupling calculations. These calculations employed a potential energy surface (PES) computed using the explicitly correlated coupled cluster method that included single, double, and (perturbatively) triple excitations [CCSD(T)-f12a] and a correlation consistent aug-cc-pVTZ basis. The geometries of the molecular partners were assumed to be fixed. The global minimum of the PES was found to have an energy of -289.1 cm^-1 relative to the energy of the separated molecules, and the equilibrium intermolecular separation equals 5.64a₀. The computed points of the PES were fit to a form suitable for time-independent quantum scattering calculations. Calculated HCNO-H₂ rate coefficients were compared with scaled previously calculated HCNO-He rate coefficients. A simple radiative transfer model was applied to HNCO and HCNO lines; the ratio of the intensities of these lines was found to vary strongly for H₂ volume densities between 10⁴ and 10⁶ cm^-3.