[Pw_forum] NaN for atomic coordinates in NEB path (nudged elastic path calculation)

[Maxim Skripnik]

I've changed the code according to the neb.diffs file and got following 
error:

      Error in routine initial_guess (1):
      something wrong: images are too close

I then checked my initial and final coordinates and found out that they 
are the same. I accidentally copied the same coordinates into 
FIRST_IMAGE and LAST_IMAGE cards. So the only "bug" in QE was that it 
didn't give a proper warning.

This is just another example for how useful internal checks of user 
inputs are. Thank you very much for helping!

Best Regards
Maxim Skripnik
Univ. Konstanz


On 10/19/2017 09:53 AM, Paolo Giannozzi wrote:
> Some time ago somebody reported something similar, or maybe I got 
> NaN's as well, don't remember. It turned out that the path had zero 
> length. I added the attached patch to the development version.
>
> Paolo
>
> On Wed, Oct 18, 2017 at 7:32 PM, Maxim Skripnik 
> <maxim.skripnik at uni-konstanz.de 
> <mailto:maxim.skripnik at uni-konstanz.de>> wrote:
>
>     Dear QE users and developers,
>
>     I'm trying to get a NEB calculation running. However, it fails
>     after the
>     SCF for image 2 with the following error:
>
>            Error in routine coset (1):
>            nsym == 0
>
>     The problem seems to lie in the initial NEB path. The file neb.path
>     contains NaN values for x,y,z coordinates for images 2-6, where
>     images 1
>     and 7 are predefined.
>
>     I found exactly the same issue here:
>     http://qe-forge.org/pipermail/pw_forum/2012-January/097544.html
>     <http://qe-forge.org/pipermail/pw_forum/2012-January/097544.html>
>     The solution there was to update to QE 4.3.2. I'm using QE 6.1.
>     Can anybody tell me why the initial path contains NaN values for
>     the atomic
>     coordinates?
>
>     I've attched the neb.in <http://neb.in>, neb.log and neb.path files.
>
>     Best regards,
>     Maxim Skripnik
>     Univ. Konstanz
>
>
>
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>
>
>
>
> -- 
> Paolo Giannozzi, Dip. Scienze Matematiche Informatiche e Fisiche,
> Univ. Udine, via delle Scienze 208, 33100 Udine, Italy
> Phone +39-0432-558216, fax +39-0432-558222
>
>
>
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