148 handle changing symmetries in vasp

[ndaelman-hu]

Tackle changing symmetries (and k-point set) between ionic updates in newer VASP versions (about 6). This solution packages kpoints into lists matching the no. calculations. The cases of single-point calculations and the older format are also handled (for vasprun.xml). No explicit information about the version is used.

Closes #148

[ndaelman-hu]

@ladinesa Should I add the test referenced in the original issue?

[ladinesa]

Thanks for the fix. Please also add a test for this, maybe one outcar and one vasprun, you can also use this for the atom positions fix.

[ndaelman-hu]

Something to consider in the future, when we clean the VASP parser. The VASP mainfiles have very different structures. Just considering the case of the frequency analysis:

• OUTCAR: k-points and eigenvalues are repeated for each ionic update + k-points are repeated at the end
• vasprun.xml: k-points (list) are repeated at each ionic update + at the beginning (under <incar>). The (electronic) eigenvalues are only printed in the last calculations step (maybe also for under the projected tag)

When it comes to eigenvalues, we mostly just need the no. irreducible k-points (at that step) to restructure the eigenvalues. Atm, we are extracting all the k-points in full, at each step, and this might be overkill. Full extraction is only needed at the last step.