, where t i is the unit vector pointing from the predecessor image, i -1, to the successor image, i + 1; cf., ref. 30). Instead of the total force from each individual relaxation step, we use averages calculated over blocks of 10 iteration steps for the convergence criterion. We verify our implementation on a model potential, V mod , with two well-defined stable states (cf., Supporting Information SI1.1). The start and end points of the input paths are perturbed away from the stable states (Figure ). We observe that the choice of the EB spring constant, k, can lead to the MEP not being traced out accurately. Especially when the spring constant, k, is large, the band gets easily stuck far away from the MEP. We resolve the issue by using a spring constant of zero and adding two algorithmic steps at the end of each EB iteration: