where R, r1, r2, and r3 are the distance between centers of mass of AB and CDE, the interatomic distance of AB, the distance from C to the center of mass of DE, and the interatomic distance of DE, respectively, with 𝜇𝜇 𝑅𝑅 , 𝜇𝜇 1 , 𝜇𝜇 2 , and 𝜇𝜇 3 as the corresponding reduced masses. 𝚥𝚥̂1 is the rotational angular momentum operator of AB, 𝑙𝑙 ̂2 is the orbital angular momentum operator along r2, and 𝚥𝚥̂3 is the rotational angular momentum operator of DE. 𝚥𝚥̂2 3 = 𝚥𝚥̂3+𝑙𝑙 ̂2 and 𝐽𝐽 ̂=𝚥𝚥̂1+𝚥𝚥̂2 3 . As the two non-reactive NH bonds are nearly spectators along the reaction path, their lengths are fixed at 1.93 𝑎𝑎 0 , leading to r2 and r3 fixed at 1.97 and 1.93 𝑎𝑎 0 , respectively.