Intrinsic-reaction-coordinate calculations: Difference between revisions

Revision as of 10:30, 7 December 2022

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]

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 The potential energy profiles along intrinsic reaction coordinate (IRC) can be computed via damped velocity Verlet algorithm of Hratchian and Schlegel<ref>[https://pubs.acs.org/doi/abs/10.1021/jp012125b H. P. Hratchian and H. B. Schlegel, J. Phys. Chem. A 106, 165 (2002).] </ref>.
+*{{TAG|IRC_DIRECTION }} direction of the initial displacement (-1|1 – negative|positive)
+*{{TAG|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)
-Experienced users can affect the performance of the dimer method by modifying the numerical values of the following parameters (the given example values are the default values):
-*{{TAG|IRC_DIRECTION }} direction of the initial displacement (-1|1 – negative|positive)
-*{{TAG|IRC_STOP}} =  20 the number of steps the energy must monotonously increase, used as a termination criterion for the DVV procedure (going from TS you expect to decrease energy till you reach a minimum (that’s the time to stop) and then energy increases again). In order to avoid a premature simulation termination (especially close to TS, i.e. at the very beginning of simulation), e.g., due to a numerical noise,  DVVEHISTORY should always be greater than 1 (10-50 usually does the job)
 *{{TAG|IRC_MINSTEP}} =    0.0250
 *{{TAG|IRC_MAXSTEP}} =    3.0000
 *{{TAG|IRC_VNORM0}} =    0.0020
 *{{TAG|IRC_DELTA0}} =    0.0015
+<references />