A quantum/classical time-dependent self-consistent field (Q/C TDSCF) approach is used to simulate the dynamics of collisions of Ar with HCO. We present state-to-state cross sections and thermal rate constants for vibrational transitions. Using this model together with assumptions about the rotational energy transfer and a master equation treatment of the kinetics, the low-pressure thermal rate of collision-induced dissociation (CID) was calculated over the 300-4000 K temperature range. A comparison with experiment shows good agreement at high temperatures and poor agreement at low temperatures. The high temperature results were sufficient to obtain an Arrhenius expression for the rate that agrees with all experimental results of which we are aware.