Existing chemical kinetics models in state-of-the-art CFD result in predictions that are not fully consistent with direct molecular simulations (DMS) based on ab-initio data. Progress toward the development and implementation of a chemical kinetics model based on a microscopic description of the gas behavior is presented. A consistent comparison between DMS and CFD is desired, so electronic energy is excluded from the CFD calculations. The model for change in vibrational energy due to dissociation is found to be important, especially for isothermal simulations. Several other individual factors are also examined. Incorporating rates derived from Boltzmann distributions results in an overprediction of the DMS dissociation rate. Capturing the depletion of vibrationally-excited molecules is found to be necessary.