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.
- IRC_DELTA0 = 0.0015 the desired error – the smaller value, the closer the computed trajectory follows the true IRC (but the more DFT steps is needed)
- IRC_MINSTEP = 0.0250
- IRC_MAXSTEP = 3.0000
- IRC_VNORM0 = 0.0020
| Mind: This method is presently available only for fixed cell shape (i.e., ISIF = 2) simulations. |
| Mind: The calculation must be initialized from a very well relaxed transition state (EDIFFG = -0.005 or less in absolute value) |