Dear developers,
I'd like to report a strange behavior of neb.x when one sets
tefield=true and dipfield=true. The error of the first image becomes
very large even though the xyz coordinates in FIRST_IMAGE are properly
relaxed. This seems to be not an issue for the actual neb calculation
since neb.p finds the energy barrier anyway. Nevertheless, it leads to a
corrupt .path file, which contains either ********** or/and NaN. When
one wants to restart the neb calculation (e.g. when going from
CI_scheme='no-CI' to 'auto'), is crashes since neb.x reads the corrupted
.path file which contains ******* and NaN.
I took a look at the pw.x calculation of the first image, which is done
only once at the beginning of a neb calculation (stored in
prefix/neb_1/PW.out). And already there one can see the problem:
end of prefix/neb_1/PW.out:
...
...
...
convergence has been achieved in 26 iterations
Writing output data file neb.save
Forces acting on atoms (Ry/au):
atom 1 type 2 force = ************** NaN**************
atom 2 type 2 force = ************** NaN**************
atom 3 type 2 force = ************** NaN**************
atom 4 type 2 force = ************** NaN**************
...
...
...
Total force = NaN Total SCF correction = 0.000109
Interestingly, this doesn't happen with the last image, which was
relaxed with exactly the same pw.x settings. This happens even with
eamp=0, as long as tefield=true and dipfield=true. I was able to
reproduce the behavior with QE 6.0 and 6.1 on two totally different
computer clusters. Any idea why this happens?
Best regards
Maxim Skripnik
University of Konstanz
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