Problem with calculating the Elastic Constants

[amorth]

Hi guys!

I am a beginner and just start working with this program and i've no experiance in python. I'm very interested in calculation an ElasticConstain from my cif file. I have follow the instructions from tutorial but in output file i recive an error.

Traceback (most recent call last):
  File "s27z.py", line 375, in <module>
    bulk_configuration.update()
  File ".\zipdir\NL\CommonConcepts\Configurations\AtomicConfiguration.py", line 1072, in update
  File ".\build\lib\site-packages\tremolox\TremoloBaseCalculator.py", line 216, in _update
  File ".\build\lib\site-packages\tremolox\TremoloBaseCalculator.py", line 715, in _configure_tremolo_model
tremolox.RuntimeError: Error in C:\cygwin\home\quantum\quantumnotes\qw-control\quantumsource\external-libs\src\tremolox\src\reaxff.c line 5549: ReaxFF data file D:\Program Files (x86)\lib\site-packages\tremolox\potentials\ReaxFF\ffield.reax.Ni_C_H does not support all needed bond pair parameters (number of needed atom type pairs 14 not equal to number of read ReaxFF type pairs 15). Please check the bonded section. If you know what you are doing, you may also set: strict_bondpairs='off'
:\Program Files (x86)\lib\site-packages\tremolox\potentials\ReaxFF\ffield.reax.Ni_C_H does not support all needed bond pair parameters (number of needed atom type pairs 14 not equal to number of read ReaxFF type pairs 15). Please check the bonded section. If you know what you are doing, you may also set: strict_bondpairs='off'

I tried to type 'strict_bondpairs='off' ' in the input, but that didn't help.

Could you provide me some tips for solving this problem?

[Julian Schneider]

This is  a problem that sometimes occurs when you choose one the ReaxFF potentials in ATK-Classical.
Essentially, it means that some of the bonds in your configuration are not supported by the potential.
If possible, you should try selecting a different potential for your system, e.g. one of the Tersoff or EAM-potentials.

[amorth]

thanks for the answer!

I have tried modified my calculation, according to your instructions, based on the information from

http://quantumwise.com/publications/tutorials/item/848-adding-combining-and-modifying-classical-potentials

but i have problem with partial charges for atoms (in my compound i have Ni, C, N, O and H).

I tried also to calculate using ATK-DFT but I gave up after 24 hours, because this method consumed too much CPU and memory.

[Julian Schneider]

Unfortunately, it looks like the ReaxFF-potentials are not suited for your system, so VNL does not provide a pre-defined potential for your system.
So, you'd either need to use DFT, or you could try searching the literature, to see if there is another potential, which may be suited for your system.
Then, we can check if this potential can easily be implemented in VNL, and in that case provide the potential as a script.