where N * i = N i /g i . The QSS distributions for both temperatures are in excellent agreement throughout the internal energy space. The largest errors are encountered in the states close to the dissociation limit, as seen in Fig. ). One possible reason for this trend can be associated with the high sensitivity of these levels to the value of the dissociation rate coefficients. Even a small discrepancy in the prediction of these quantities can lead to a difference in the predicted state population. Nonetheless, the error in the QSS distribution is within 10%. Additionally, Fig. compares the SurQCT-based population distribution for 8, 000 K and 20, 000 K at simulation time outside QSS (i.e., t = 1e-7 s) with the reference solutions obtained using QCTbased ones. It should be noted how the vibrational strands separating below -4 eV are accurately captured by SurQCT, despite the discrepancies in predicting the populations of high-energy states. Finally, the population distribution profiles for the recombining scenario are shown in Fig. . The population distribution function is plotted for two bath temperatures, T = 1, 500 and 2, 500 K. Since the recombination happens through the tail of the distribution, getting an accurate description of this region is indicative of SurQCT accuracy.