STATE-SPECIFIC DISSOCIATION RATES FOR H₂(v, j) + H₂(v′, j′)

Abstract

State-specific rate coefficients for the dissociation of H 2 as the result of collisions with H 2 were calculated for all combinations of (v, j) with an internal energy below 1 eV. Full-dimensional quasiclassical trajectories were calculated using the BMKP2 interaction potential with a minimum of 80,000 trajectories at each translational energy. Additional large batches of trajectories were carried out to calculate the cross sections near the threshold to dissociation to attain the desired precision of the rate coefficients. A piecewise linear excitation function was used to calculate the rate coefficient between 100 and 100,000 K. The resulting state-specific rate coefficients, γ, were parametrized as a function of temperature over the range 600-10,000 K using:10 2 where = t T 4500 K and = z t log 10 . The values of the resulting rate coefficients were sensitive to the internal energy of both molecules, with initial vibrational energy having a slightly greater effect than rotational energy. This effect diminished as temperature increased.

Signatures of Hot Molecular Hydrogen Absorption from Protoplanetary Disks. I. Non-thermal Populations

“…The rate of collisions between H 2 + e − , for gas with T gas ∼ 3500 K, is found to be C H2,e − ∼ 10 −11 cm 3 s−1 (Prasad & Huntress 1980). Additionally, interactions between H 2 + H 2 are expected to occur much less frequently, with C H2,H2 ∼ 10 −16 cm 3 s−1 for T gas ∼ 3500 K (Mandy 2016).…”