= 0 if atom i is not a part of the distance R k between atoms a k and b k (i.e., i a k and i b k ). In the other case, when, say, i = a k and j = b k , and thus R k = R i j = (r i -r j ) 2 , then We implemented the proposed MTD routine into the BBBMTD script of the PyRAMD software. To demonstrate the algorithm's performance, we chose two prototypical reactions: proton transfer between two oxygens in the enol form of the malonaldehyde and decomposition of the cyclohexene into the 1,3-butadiene and ethylene, which is the inverse of the Diels-Alder reaction. The schematics of these reactions are given in the insets (a) of Figs. and, respectively.