When comparing downhill AL and WTMetaD-IB AL, WTMetaD-IB AL shows slightly lower energy and force errors (1.83 meV atom -1 and 93.29 meV Å -1 , respectively) compared to downhill AL (2.14 meV atom -1 and 115.74 meV Å -1 ), as depicted at Fig. and. The marginally better performance for WTMetaD-IB can be attributed to its more uniform sampling across the energy and reaction coordinate space (Fig. ). Downhill AL demonstrates higher accuracy around the TS region, defined as configurations with r Cl -r F ±0.1 Å from the optimized TS (dashed line in Figure and), with energy and force errors of 1.71 meV atom -1 and 74.99 meV Å -1 , respectively. The PS region, similarly defined by the deviation from the optimized PS (dashed line in Fig. and) within ±0.1 Å, shows the largest energy prediction error along the IRC for both methods (Fig. ). However, these inaccuracies are not observed in the testing data generated from US/AIMD simulations. The contrasting MLP performance on the two test sets arises from the different configurations generated by IRC and US/AIMD, where the former presents an idealized scenario, with the Cl-C-F bond angle remaining almost constant at 180°during the reaction, while during US/AIMD, it ranges from 150°to 180°illustrating the dynamic nature of the reactive processes (Fig. ).Overall, while WTMetaD-IB AL requires more iterations than downhill AL, its Free Energy Barriers through the WTMetaD-IB AL Approach -