search

nomad-coe / electronic-parsers

Apache License 2.0
18 stars 7 forks source link

Handle changing symmetries in VASP #148

Open ndaelman-hu opened 11 months ago

ndaelman-hu commented 11 months ago

During a geometry optimization or frequency calculation, the symmetry of the cell can change. When symmetry-reduction is active, the number of reduced k-point can change by ionic update. This causes errors when reshaping eigenvalues extracted from the OUTCAR, which are contingent on the (original) no. irreducible k-points:

"root":{
  "event":string"Error reading eigenvalues"
  "proc":string"Entry"
  "process":string"process_entry"
  "process_worker_id":string"QrhFb34pRf6tYAkBJQqhpQ"
  "parser":string"parsers/vasp"
  "step":string"parsers/vasp"
  "logger":string"nomad.processing"
  "timestamp":string"2023-08-17 16:19.03"
  "level":string"ERROR"
}

The frequency calculation that brought this error to light: trash:///freqsafd_pbe.zip

ndaelman-hu commented 11 months ago

Note: when the ionic positions are updated and the main file is vasprun.xml, the <kpoints> should be derived from <calculations>, else from the "standalone" tag (under <modeling>).

ndaelman-hu commented 11 months ago

This is apparently a new VASP feature (as of version 6?), so especially with vasprun.xml one has to distinguish between the placement of <kpoints>: under modeling or calculation (only in newer versions, not sure about the single-point case).

ndaelman-hu commented 11 months ago

Correction, the cause is not the VASP version, but the routines chosen to perform frequency / phonon calculations. I came to this conclusion after finding another example that uses IBRION = 6: entry_id = y0MhHRV_TIb_zamDSdM2QB6o84bF