Phonon Stability Screening

What This Tool Does

Filter uploaded CIF structures by ML-potential phonon dynamic-stability screening.

Typical Inputs

• CIF files, or a ZIP/TAR.GZ archive containing CIF files.
• Screening preset: tolerant, strict, or custom.
• Supercell, q-mesh, displacement amplitude, and imaginary-frequency threshold.

Access And Computing Limits

This is a computing-intensive app and requires login. Free daily CIF limits are counted after archive expansion: unverified users can submit 3 CIFs per day, verified non-academic users can submit 10 CIFs per day, and verified academic users can submit 50 CIFs per day. Submissions above the daily free limit consume computing credits when credits are available.

Method

The app uses MatterSim ML-potential forces with phonopy finite displacements by default. For each CIF, it builds displaced supercells, evaluates forces, constructs force constants, samples the selected q-mesh, and flags structures with frequencies below the negative imaginary threshold. Nequix remains an optional advanced backend for deployments that explicitly install it, but MatterSim is the primary local and remote screening path.

Output

• phonon-screening-results.csv with formula, minimum frequency, imaginary-mode magnitude, modes below threshold, and pass/fail status.
• phonon-screening-passing-cifs.zip containing only CIFs with no imaginary modes beyond the selected threshold.

Presets

• Tolerant: 0.10 THz imaginary-mode tolerance.
• Strict: 0.03 THz imaginary-mode tolerance.
• Custom: use the selected imaginary threshold.

Limitations

This is ML-potential screening, not final DFT proof. Small negative acoustic frequencies can be numerical artifacts, and soft-mode materials may need relaxation, larger supercells, denser meshes, smaller displacements, temperature-aware analysis, or DFT/experimental confirmation.