I have an issue during QTS3 and TS searches. In a particular arrangement I am finding the last step reports:
Maximum Force 0.013634 0.000450 NO
RMS Force 0.003018 0.000300 NO
Maximum Displacement 0.000083 0.001800 YES
RMS Displacement 0.000010 0.001200 YES
Predicted change in Energy= 8.060815D-07
Followed then by the error:
GradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGradGrad
Berny optimization.
Bend failed for angle 3 - 14 - 49
Tors failed for dihedral 2 - 3 - 14 - 49
Tors failed for dihedral 4 - 3 - 14 - 49
Tors failed for dihedral 5 - 3 - 14 - 49
Tors failed for dihedral 3 - 14 - 49 - 50
Tors failed for dihedral 3 - 14 - 49 - 51
FormBX had a problem.
Any idea why the force is failing to converge by the displacement is not? That just doesn't seem to make sense.
Thanks
Anthony
Dear Anthony,
The reason for Gaussian to stop is that during the optimization, the angle formed by atoms 3-14-49 adopts a weird value. Re-define your initial structure or do a slight modification on this angle at the point the run failed. It is not related to force and displacement, as each has its own threshold for convergence.
Thanks Miguel,
I suspected that was the case. I checked Bend failed for angle 3 - 14 - 49 and it was 180 degrees. I guess that broke the search algorithm. I was just quite surprised to see this as an immediate result of the displacement converging before the force.
Thanks
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