[CP2K-user] Wrong Endpoint Energy in NEB Calculation
fabia... at gmail.com
Sat Mar 14 13:24:16 UTC 2020
The culprits are
If you change those to
both endpoint energies agree:
-934.347897297 -934.316490032 -934.289348456
-934.274499318 -934.304688658 -934.347897299
As far as I know, these two keywords are only to be used with molecules
without periodic boundaries.
On Saturday, 14 March 2020 14:02:47 UTC+1, Martin Brehm wrote:
> Dear Community,
> we performed a CP2K NEB calculation of a solid state system. The starting
> and ending configuration of the band are equivalent after wrapping
> coordinates into the primary image of the cell (just two atoms have changed
> place, one of them moving out of the primary image). This can easily be
> confirmed by running single point calculations of the starting and ending
> calculations - they yield identical energies in CP2k.
> When we now perform the NEB calculation, the ending point unexpectedly
> yields a different total energy (too high by 13.1 kJ/mol). The starting and
> ending configuration cannot move during the NEB optimization, as we
> specified "OPTIMIZE_END_POINTS .FALSE.". And the energy of the starting and
> ending configuration remains constant during the NEB optimization - the
> strange higher energy appears from the beginning on. So this problem is
> probably not related to the NEB calculation itself.
> Attached ("image_energy.png") you can find a plot of the total energy of
> the NEB images at some point during the NEB optimization, where the first
> and the last value should be identical.
> We already checked the following:
> (*) We tried to simply swap the starting and ending geometry. Then, again,
> the energy of the ending geometry is higher by the same amount (13.1
> kJ/mol), and the energy of the starting geometry is correct this time. This
> confirms that both configurations are identical. Probably there is a bug
> which affects the energy calculation of the last image in a NEB calculation.
> (*) We were able to reproduce this error on different computer systems,
> using different CP2k versions, from 2016 to recent versions.
> (*) Even the contribution of the dispersion correction to the last NEB
> image is different than to the first one. This indicates that the issue is
> not related to the SCF calculation, but that somehow the geometry of the
> last image is not correct in the internal data structures.
> The following files are attached to this post:
> image_energy.png - Plot of the total energy of the NEB images at some
> point during the NEB optimization.
> band.inp - Input file for the NEB run.
> start.xyz - Starting configuration (first NEB image).
> end.xyz - Ending configuration (last NEB image).
> coord.xyz - Again the coordinates for the "&COORD" section.
> li12si7-BAND01.out - Beginning of the Log file for the first NEB image.
> li12si7-BAND16.out - Beginning of the Log file for the last NEB image.
> If you want to try to reproduce this strange behavior, you do not need to
> wait until the NEB calculation is converged. Already one or two geometry
> steps will be sufficient to check if the first and last (fixed) images have
> identical energies (as they should) or not.
> Any recommendations are welcome.
> Best regards,
-------------- next part --------------
An HTML attachment was scrubbed...
More information about the CP2K-user