Intrinsic-reaction-coordinate calculations

The potential energy profiles along intrinsic reaction coordinate (IRC) can be computed via damped velocity Verlet algorithm of Hratchian and Schlegel^[1].

IRC_DIRECTION direction of the initial displacement (-1|1 – negative|positive)
IRC_STOP = 20 the number of steps the energy must monotonously increase before the algorithm terminates. In order to avoid a premature terminations, especially close to transition states., e.g., due to a numerical noise, IRC_STOP should always be greater than 1 (10-50 usually does the job)
IRC_MINSTEP = 0.0250
IRC_MAXSTEP = 3.0000
IRC_VNORM0 = 0.0020
IRC_DELTA0 = 0.0015

↑ H. P. Hratchian and H. B. Schlegel, J. Phys. Chem. A 106, 165 (2002).

[1] H. P. Hratchian and H. B. Schlegel, J. Phys. Chem. A 106, 165 (2002).

[1]