Phonon Displacement Workflow

1. Generate the displacement set explicitly

• Keep the supercell size and displacement amplitude visible in the workflow record.
• If the backend falls back to a manual generator, report that instead of assuming symmetry reduction happened.

2. Run force jobs, not generic relax jobs

• Prepare the displacement set for force evaluation under one method contract.
• Use static/force semantics for the displaced structures; do not quietly relax the displaced cells or ionic positions.
• If the phonon workflow requires symmetry to stay off for the displaced structures, surface ISYM=0 explicitly rather than assuming the wrapper will infer it.
• Do not mix displacement generation and phonon fitting logic in one opaque step.

3. Collect only accepted force runs

• Use analyze_vasp_results to identify failed or unconverged force points before any later phonon fitting.
• Keep a displacement-to-calculation ledger so later fitting can map every force set back to its displacement ID.

4. Hand off only a complete force dataset

• If any displacement member failed, report the collection as partial instead of implying phonon readiness.
• Keep the generation backend note (phonopy vs fallback) with the force-job summary.

Method-critical defaults

• Keep ENCUT, k-point density, spin treatment, and any DFT+U/dispersion toggles fixed across every displacement.
• Do not relax displaced structures during force collection; the target observable is the force response of the displaced geometry.
• Keep symmetry handling explicit for displaced jobs when that matters to the force-set interpretation.
• Report supercell and displacement amplitude explicitly because both affect the eventual phonon interpretation.

Output Contract

Return:

• displacement metadata path
• prepared/executed batch root
• VASP analysis summary path
• any note about phonopy vs fallback generation
• displacement-to-calculation mapping ledger

References

• This skill stops at force-collection readiness; phonon DOS/band fitting should be handled as a separate analysis stage.