Three simulations were run for each system using GaMD-WE and WE, and average of the three is shown as the final result for all systems. Error bars for WE and GaMD-WE rate constants represent 95% confidence intervals (i.e., 1.96 × σ √ 3 where σ denotes standard deviation). Each point in WE and GaMD-WE rate constant graph was calculated cumulatively in 50 iteration blocks.