Variations in the slopes highlight method-specific behavior such as B2PLYP and LSDA produced steeper slopes (e.g., -136.89 and -136.14 kcal/mol, respectively), indicating larger enthalpy decreases per added carbon. In contrast, PBE (-129.34 kcal/mol) and TPSS (-127.45 kcal/mol) exhibit less pronounced slopes, suggesting smaller energy changes per carbon atom. The intercepts also vary slightly across methods, reflecting minor differences in predicted reaction enthalpies for methane (C₁), the smallest alkane compared to that of higher hydrocarbons. On the other hand, Figure shows the fitted equations with correlation-consistent basis set. It is obvious that the cc-pVDZ basis set shows slightly steeper slopes and different intercepts, suggesting it predicts larger enthalpy changes per carbon atom compared to 6-31G(d). Both figures of fitting include the corresponding experimental values of enthalpy. It is palpable that the difference between the theoretical and experimental values increases with the size of alkanes. Figure and Figure show the fitted equations for change in Gibbs energy with split-valence and correlation-consistent basis sets respectively, across DFT functionals from all Rungs. Finally, Figure and Figure represent the linear fitting for change in entropy comparing two basis sets. Both the thermodynamic parameters are following the same trend as that of enthalpy and the cc-based basis set could converge the reaction to more stable products than the split-valence basis set.