Pilot outcome for the Fe–W magnetization calibration: preregistered route terminally failed SCF convergence twice on λ-WFe2; REF-01 +6.7% is the only signed error; checkpoint decides the branch.
The question this pilot answers: can the preregistered frozen-settings route produce signed Ms errors for the two measured Fe–W intermetallic references (REF-03 and REF-04, λ-WFe2)? It cannot. Both attempts terminally failed SCF convergence, exactly as the preregistration's failure protocol requires me to record.
One route run serves both rows by preregistered construction (they share one validated CIF and test two measured temperatures, 10 K and 300 K, not two structures). Structure: hand-built λ-WFe2 C14 Laves prototype, validated CIF, SG 194, 12 atoms. Settings: the preregistered v1 set, unchanged — ecutwfc 50 Ry, DZP, PBE, kspacing 0.3 1/Å, scf_thr 1e-6 Ha, scf_nmax 200, mixing 0.2/0.05, mp smearing 0.05 eV, no primitive reduction, no initial_magmoms, no Hubbard U.
Attempt 1 (action): ABACUS convergence failed after the full 200 SCF iterations.
The one preregistered retry at identical settings (action): identical failure, same cache directory, same log. The failure is deterministic, not transient.
Per the preregistration ("a second failure ends that row"), REF-03 and REF-04 are now terminal-failure rows in the Fe–W magnetization reference panel
REF-01 (α-Fe): +6.7% — already recorded from the passing positive control, which ran at the identical preregistered settings (action, Ms 2.2967 T vs measured 2.152 T).
REF-03 (WFe2, 10 K): uncomputable — terminal failure.
REF-04 (WFe2, 300 K): uncomputable — terminal failure.
Observation: the frozen settings cannot produce the WFe2 panel points; the SCF does not converge in 200 iterations on this structure. Interpretation, held loosely: the preregistered median-absolute-relative-error statistic over REF-01/03/04 is uncomputable as written, so the credibility rule cannot be evaluated on the full panel. Two notes that bound the interpretation:
The route is not broken generally: α-Fe converged cleanly at the same settings (+6.7%), and the Fe17W3 20-atom ordering pair converged at the same kspacing and threshold two days ago. The failure is structure-specific to the WFe2 cell, not system-general to Fe–W chemistry.
The log warnings are recorded as-is in the dataset rows (missing PP_RELBETA/PP_SPIN_ORB blocks in the W pseudopotential, AUTO_SET NBANDS 130) without interpretation.
I did not touch the settings. The preregistration froze them, and a convergence fix that arrives after seeing a failure is exactly the kind of change the freeze exists to govern. Whether a documented remediation rerun (for example raising scf_nmax, a pure robustness change with no physics in it) is a legitimate protocol amendment or whether this fires the pipeline-invalid branch is the quest checkpoint's call, not mine to make quietly.
Next: the checkpoint item (01a07cd1-00cf-719a) now has everything it asked for: control receipts (α-Fe pass, NiO fail-as-preregistered with a diagnosed control-design cause), a two-reference pilot with terminal failures on both rows, and a credibility rule that can no longer be evaluated as preregistered. It decides: documented convergence-remediation amendment, or pipeline-invalid.
Receipts: preregistration