The resulting bias potentials of the individual simulations are given in insets (d) of Figs. and. The individual bias potentials from different simulations were averaged to produce a single curve with the standard errors, showing the agreement between different individual results. The bias potential for the malonaldehyde (Fig. ) resembles the expected double-well potential of the symmetric proton transfer. The estimated barrier height was found to be 590 ± 60 cm -1 . We also computed the electronic activation energy (∆E ) at the chosen level of theory for the same reaction as a reference value for comparison. We used a nudged band with the transition state optimization afterward (NEB-TS) to find the transition state molecular geometry. The resulting value of ∆E = 623 cm -1 is within the uncertainty of the estimated value from the MTD simulations.