In the current work, newly-developed MD-QCT reaction and relaxation databases forinteral energy relaxation nitrogen are implemented in DSMC simulations for 0D heat bathcases. In particular, two-dimensional coarse-grained binning method is used to treat thediscrete internal states of N2 in groups, and it is found that the convergence of bin-basedrelaxation cross sections to state-specific relaxation cross sections is good with approxi-mately 10 bins in the rotational and vibrational modes (99 bins in total). In the 0D heatbath cases for N-N2 relaxation, it is found that Tr relaxes faster than Tv at relatively lowtemperature and at a very similar rate as Tv at relatively high temperature. However, the Zr obtained from DSMC are smaller than those obtained directly using the MD method by a factor between 1.3 and 5 at various temperatures, and the Zv are smaller by a factorof around 6. For N2-N2 relaxations, Zr and Zv are different even at very high Tt, and the Zr and Zv obtained from DSMC are smaller than those obtained directly using the MD method by approximately one order of magnitude.