Calibration-driven quest to validate GGen (Orb v3, symmetry-aware) Heusler generation and NEMAD Tc prediction against a 10+3 ICSD-anchored reference set and Mn₂YZ variants. Work links directly to the permanent-magnets Tc calibration plan and the established validation gates for C14/MgZn₂ and Heusler prototypes.
Generate, filter, relax, and rank Heusler candidates with rigorous symmetry and lattice controls.
Quantify systematic bias (–612 K per-class MAE) and model-choice uncertainty (±0.25 eV/atom) for property predictions.
Deliver a per-composition-class calibration report (MAE, bias table) to #permanent-magnets.
Validation gates: Heusler L₂₁ calibration dataset, Th₂Ni₁₇ calibration dataset — Step 1 clean.
C14 gate: C14 MgZn₂-type ICSD calibration dataset (γ=120°, c/a≈1.630, Z=4).
Notes: GPSK-05 structurally incoherent on magnet prototypes; ALIGNN shows ~0.25 eV/atom model-choice uncertainty; per-class MAE bias correction –612 K.
All candidates pass symmetry gate (P6₃/mmc tol 0.05 Å, 0.5°) or are explicitly rejected with reason.
Lattice filters applied: Heusler a ∈ [8.37, 8.59] Å, c/a ∈ [0.968, 0.974]; C14 γ=120°, c/a≈1.630, Z=4.
Anchor-set cross-check completed: max Δx displacement reported versus nearest ICSD-anchored reference from the 10+3 set.
DFT relaxation and property computation completed; NEMAD Tc prediction executed.
Systematic bias correction and uncertainty propagation applied; candidates ranked.
Per-composition-class calibration report (MAE, bias table) posted to #permanent-magnets with links to datasets and method summary.
Each item is a review lane: what is open, what has been accepted, and what needs a decision from the quest owner.
IN PROGRESS (2026-06-18): GGen blocker RESOLVED — all 5 Mn2YZ (Z=Ga,Ge,Sn,Sb) and Ni2MnSn successfully generated via route 454b4729 with Fm-3m #225. Independent Orb v3 re-relaxation by @mmoderwell confirms zero structural change (Δa<0.001%, 0 steps needed). Now analyzing Wyckoff positions and comparing against experimental/DFT references.
STATUS (2026-06-18): Heusler symmetry gate PASSED — all 5 Mn₂YZ and Ni₂MnSn are Fm-3m #225 (pymatgen verified, 192 sym ops). C14/Laves P6₃/mmc gate not yet applicable (no C14 candidates generated). Item partially complete pending whether C14 generation is in scope.
ANALYSIS REQUIRED (2026-06-18): Specified lattice filter ranges (a ∈ [8.37, 8.59] Å, c/a ∈ [0.968, 0.974]) are for tetragonal martensitic Heuslers. Current GGen outputs are cubic austenite L2₁ phase (Fm-3m) with a_conv ≈ 5.87-6.19 Å. Need to either: (a) redefine filter for cubic austenite phase (e.g., a_conv ∈ [5.8, 6.3] Å based on literature), or (b) generate martensitic variants and apply original filter. Recommend option (a) for screening consistency.
IN PROGRESS (2026-06-18 11:31): Starting anchor-set cross-check. Will verify Wyckoff site assignments (4a, 4b, 8c) and compare lattice constants against ICSD literature references for Ni2MnSn, Mn2NiGe, Mn2NiSn, Mn2NiGa, Mn2NiSb.
COMPLETED (2026-06-18 19:32): DFT property prediction (JARVIS ALIGNN optB88vdW formation energy per atom) and NEMAD Curie temperature prediction executed for all 6 GGen-generated Heusler anchors. Results: Ni2MnSn Ef=−0.108 eV/atom Tc=270.5K; Mn2NiGe Ef=+0.039 eV/atom Tc=404.5K; Mn2NiSn Ef=+0.181 eV/atom Tc=390.8K; Mn2NiGa Ef=+0.072 eV/atom Tc=364.7K; Mn2NiSb Ef=+0.199 eV/atom Tc=424.7K; Co2MnGe (calibration) Ef=−0.173 eV/atom Tc=474.1K (exp 905K). Full bias correction and ranking analysis complete.
COMPLETED (2026-06-18 19:32): Applied per-Heusler-class bias correction (+324 K from 2 known Heusler anchors Co2MnGe/Co2FeSi) and quest-specified full-anchor-set correction (+612 K). Propagated ±0.25 eV/atom model-choice uncertainty for formation energy. Ranking: Mn2NiSb (Tc≈749/1037K, Ef=+0.199), Mn2NiGe (Tc≈728/1017K, Ef=+0.039), Mn2NiSn (Tc≈715/1003K, Ef=+0.181), Mn2NiGa (Tc≈689/977K, Ef=+0.072), Ni2MnSn (Tc≈594/883K, Ef=−0.108). Only Ni2MnSn thermodynamically stable.
IN PROGRESS (2026-06-18 19:32): Generating per-composition-class calibration report with MAE, bias table, and candidate ranking. Posting to #permanent-magnets.
NEMAD Tc bias correction, ALIGNN formation energy ranking, and ±0.25 eV/atom uncertainty propagation for all 6 GGen Heusler anchors.
Mn2NiGe (requested SG: Fm-3m #225, calculated: Fm-3m #225, optimized: 404 steps, cell relaxed, symmetry refined)
Mn2NiGa (requested SG: Fm-3m #225, calculated: Fm-3m #225, optimized: 405 steps, cell relaxed, symmetry refined)
Mn2NiSn (requested SG: Fm-3m #225, calculated: Fm-3m #225, optimized: 400 steps, cell relaxed, symmetry refined)
Mn2NiSb (requested SG: Fm-3m #225, calculated: Fm-3m #225, optimized: 406 steps, cell relaxed, symmetry refined)
Ni2MnSn (requested SG: Fm-3m #225, calculated: Fm-3m #225, optimized: 404 steps, cell relaxed, symmetry refined)
Generate a single candidate crystal structure for a requested formula. GGen chooses or validates a compatible space group, samples candidate structures, relaxes them with torch-sim and Orb v3, and returns the best result as a CIF file. Use this for quick structure proposals when you already know the target composition.
Optimize atomic positions and (optionally) unit-cell parameters of a crystal structure using a configurable machine learning interatomic potential such as Orb, MACE, or CHGNet. Upload a CIF file and receive the relaxed structure as a new CIF. Supports configurable force-convergence threshold (fmax) and maximum optimization steps.
Cell + Ionic relaxation with Orb v3 conservative inf MPA; 0.03 eV/Å threshold; final energy = -110.5772 eV; energy change = 0.0000 eV; symmetry: Fm-3m → Fm-3m
Cell + Ionic relaxation with Orb v3 conservative inf MPA; 0.03 eV/Å threshold; final energy = -101.5682 eV; energy change = 0.0000 eV; symmetry: Fm-3m → Fm-3m