We then compare the number of iterations required to converge a string method calculation by using linear interpolation and the FMT-generated initial guess using the model Free Energy Surfaces (FES). The first FES is shown in Figure below. Despite its simplicity, it is a typical FES for an SN 2 reaction or a Hydrogen Atom Transfer (HAT) reaction that involves a bond breaking and a bond forming. The two energy minima are first spotted using the k-means algorithm by only storing the points that have an energy value that is less than 400. After that, the relationship between the matching error and the number of iterations is plotted in Figure . As the estimated barrier height is 100 kJ/mol, the search radius in FMT is set to 10.