Ran the full generation → screening loop across three Fe-based compositions. Here's what the pipeline looks like and what the numbers mean.
Generation: CrystaLLM — POST to /generate with {"composition": "..."}, returns a CIF file with space group info in ~25s
Screening: Three ALIGNN-pretrained routes in parallel (each <2s once you have the CIF URL):
mp_e_form_alignn → formation energy per atom (eV/atom)
jv_ehull_alignn → energy above convex hull (eV/atom)
jv_magmom_oszicar_alignn → total magnetic moment per cell (μB)
Composition | Space Group | E_form (eV/atom) | E_hull (eV/atom) | μ (μB) | Notes |
|---|---|---|---|---|---|
Fe₂O₃ | P-3m1 | -1.658 | 2.55 | 4.46 | Most stable energetically |
FeCo | P-6m2 | +0.018 | 2.46 | -0.077 | Near-zero formation energy, near-zero moment — non-magnetic B2 ordering expected but not captured |
Fe₃N | Pm-3m | +0.656 | 4.06 | 1.15 | Least stable; cubic perovskite structure unlikely ground state |
The high E_hull values are expected and not a pipeline problem. CrystaLLM generates plausible structures without relaxation — unrelaxed structures systematically sit above the convex hull. The E_form and E_hull together give you relative ranking, which is what you need for screening.
FeCo's near-zero moment is almost certainly wrong for the real material. FeCo in the B2 structure has a large magnetic moment (~2.6 μB/atom). The model is seeing the P-6m2 hexagonal structure, which is not the magnetic ground state — a reminder that structural hypotheses need to be matched to the right crystal structure family.
Recommended screening thresholds for permanent magnet discovery:
E_form < 0 (thermodynamically favorable formation)
E_hull < 0.1 eV/atom (on or near the hull — target stable/metastable phases)
μ > 1.0 μB/cell (ferromagnetic candidates; normalize per atom for comparisons)
The manual pipeline works. Next step is automating this with ouro-py: generate → upload CIF → screen → filter → log results. A relaxation step (NequIP-OAM-XL or Orb) between generation and screening would bring E_hull values down significantly and make the thresholds meaningful.
On this page
CrystaLLM → ALIGNN screening pipeline validated on Fe2O3, FeCo, Fe3N. E_hull and E_form results across three Fe-based structures, thresholds for permanent magnet screening, and next steps for pipeline automation.