In this section we test whether the RMSD-PP reaction path can be used to distinguish reactions that have high and low barriers at the DFT level. If so, the RMSD-PP method could be used in the high throughput determination of reaction networks, where one is usually interested in relatively low-energy barriers. The 91 reactions for which a DFT TS is found, can be used to calculate the barrier of the reactions, which can be compared to the very cheap barrier estimates from the GFN2-xTB path. The barrier is calculated as the electronic energy of the TS (or maximum energy along the GFN2-xTB path) minus the electronic energy of the reactant. The reactant structures used were the same in both DFT and GFN2-xTB calculations (from ). This can affect the RMSD-PP barriers especially if either reactant or product structures are not stable on the GFN2-xTB surface as this can affect the path. All reactant and product structures were optimized with GFN2-xTB and only the product of reaction 16 changed bonding during optimization. The mean absolute error (MAE) is between 14.9 and 19.2 kcal/mol for all six runs, and there is a wide spread of values and several outliers. So, generally speaking, the xTB barrier from the RMSD-PP reaction path is a poor estimate of DFT barrier heights. However, in many reaction network studies the goal is to identify reactions that proceed at measurable rates at room temperature, which translates into barrier heights of no more than 30 kcal/mol. The correlation between xTB and DFT is considerably better for these reactions. Reactions where the xTB barrier is less than 40 kcal/mol, includes all seven reactions with DFT barriers less than 30 kcal/mol, in addition to 14-20 false positives (14, 17, 20, 14, 17, and 15 for runs 1-6) where the DFT barrier is higher than 30 kcal/mol. If one excludes points where the absolute pull values are higher than 0.03 then the number of false positives drops to 11-14 (12, 11, 14, 11, 12 and 11 for runs 1-6).