Request: energy and forces parsing

[abelcarreras]

Hi,

I would like to use AiiDA to make phonon calculations.
Therefore I need this plugin to parse at least total energy and atomic forces to be able to test it.
I suggest to use the same quantumespresso scheme:
Energy in output_parameters node (ParametersData) and forces in output_array node (ArrayData).
Also to parse stress tensor would be nice.

I think it is important to keep the output structure as close as possible among all the plugins.
Then, developing workflows that work using many codes is much easier.

Thanks,

[greschd]

Hi,

I agree that we should keep the QE and VASP plugins as close in interface as possible. As a side note, I think it's still a good idea to have an adapter for the DFT plugins in the workflow to allow catching inconsistencies in these plugins.

More to the topic at hand: Do you have or know of an existing parser for total energy and forces we could include in the plugin? Also, do you know if this information is contained in the vasprun.xml file?

[abelcarreras]

Yes, all that information is contained in the vasprun.

It is possible to use pymatgen to parse this file. For now
I think it is a fast way to implement the parsing but in the
future I think we should consider to implement it using xml
python library (which is the one used by pymatgen).

Some things are not parsed in pymatgen such us born charges (which I need).
Currently I am using Mario's old vasp plugin and I made many modifications
for parsing those things. It is pretty simple I can share the code if you want.

[DropD]

Yes, that would be very helpful. Absolutely ideal would also be a vasprun.xml file with the corresponding output of the parser, so we can easily test for correctness.

[abelcarreras]

I prepared a very minimal example of vasprun.xml parsing using both pymatgen and xml library
https://github.com/abelcarreras/vasp_parser.

Of course you can also see how this is implemented in Mario's plugin but it is really dirty now:
https://github.com/abelcarreras/aiida_extensions/blob/development/plugins/parsers/vasp/instruction/data/array_data_parser.py
https://github.com/abelcarreras/aiida_extensions/blob/development/plugins/parsers/vasp/instruction/data/output_parameters.py

[DropD]

Implemented as of #53