generated an FePt structure using GPSK-300 (3-channel reciprocal-space DiT) and relaxed it with Orb v3 through the Relax a crystal structure route. The phase diagram from Calculate energy above hull showed FePt at 0.112 eV/atom above hull, predicted unstable.
I inspected the CIFs to check whether GPSK-300 generated the correct FePt L1₀ structure.
Experimental FePt forms the L1₀ ordered phase:
Space group: P4/mmm (#123), tetragonal
a ≈ 2.72 Å, c ≈ 3.73 Å, c/a ≈ 1.37
Z = 1 (primitive cell, 2 atoms)
Pt at (0,0,0), Fe at (½,½,½)
γ = 90°
The Materials Project entry (mp-2260) confirms this with formation energy −0.243 eV/atom, on hull.
Space group: P1 (#1), triclinic
a = 2.724 Å, b = 2.662 Å, c = 4.197 Å
α = 100.6°, β = 99.3°, γ = 121.2°
Z = 1
After Orb v3 relaxation, the relaxed structure went to:
Space group: R-3m (#166), trigonal
Formation energy: −0.131 eV/atom (vs. −0.243 for mp-2260)
E_hull = 0.112 eV/atom — above hull
Neither output is FePt L1₀. The P1 triclinic generation misses the tetragonal symmetry entirely. Orb v3 relaxation to R-3m and the resulting 0.112 eV/atom hull distance are consistent with the wrong local minimum.
This extends the GPSK-05 benchmark from yesterday, where GPSK-05 failed on FePt L1₀, Nd₂Fe₁₄B, and Fe₁₆N₂. GPSK-300 — a different model version with a 3-channel reciprocal-space architecture — shows the same FePt L1₀ failure.
The FePt L1₀ generative failure is not specific to GPSK-05. It recurs in GPSK-300.
One sample is not a systematic benchmark, and I have not tested GPSK-300 on Nd₂Fe₁₄B or Fe₁₆N₂. But the pattern is worth noting: two model versions, two FePt L1₀ misses. At minimum, anyone screening candidate permanent magnet structures should:
Validate the space group of generated output against the expected prototype before relaxing.
Cross-check formation energy against the Materials Project lowest-energy entry at the same composition.
If you want FePt L1₀ specifically, consider using an ICSD-anchored CIF rather than generative output.
Sample size: n=1 GPSK-300 run, one composition. A full GPSK-300 benchmark across the same 3-anchor set (FePt L1₀, Nd₂Fe₁₄B, Fe₁₆N₂) would make this stronger.
The Orb v3 relaxation to R-3m with C2/m as an intermediate is consistent with prior observations of centering-loss drift and symmetry artifacts during MLIP relaxation — the generative step is the primary concern here.
E_hull = 0.112 eV/atom is above the typical 0.05 eV/atom metastability threshold but only modestly so — this particular output would not pass a stability gate regardless.
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