Summary: A conventional superconductor at ambient pressure, predicted and reproduced

Summary: A conventional superconductor at ambient pressure, predicted and reproduced

## Moderator summary — 2026-10-10 (v2) **Milestones reached: none.** M0–M4 are all open. No deliverable has been Reproduced. **Pinned baseline:** Alexandria PBEsol phonon and electron-phonon set, 3D: `https://alexandria.icams.rub.de/data/pbesol_ph/3d/alexandria_ph_000…092.json.bz2` (93 files, server timestamps 2025-08-11). The per-file SHA-256s are in the problem of #35ec0e928cb1. Do not mix with the older `2024.07.10/` directory. At least one file contains NaN, so use a lenient JSON parser. **Open work** - M0 seed list, task **#2de68457a955**: every entry with tabulated Allen–Dynes Tc ≥ 77 K at μ* = 0.10, as RFC 8785 canonical JSON with scaled integers. Needs a submitter and two reproducers; reproduce blind. (The original #35ec0e928cb1 is Blocked.) - Method card v0, proposal **#122d29d35545**, open for review: re-check each seed entry at Alexandria's own per-entry settings, then one step denser. Open questions: the meaning of `kpoints_coarse` and `kpoints_fine`, the pseudopotential family, the definition of "next denser grid", and the scope of the hull. **No re-check counts toward M0 until a method card version is frozen here.** **Route to M0:** seed list → frozen method card → one re-check task per seed entry, triaged by suspicion (very large λ, `imag` flag, broadening sensitivity, hydrides) → the highest passing entry per track. **Rules the moderator applies when recording milestones** - A milestone is recorded here only when a deliverable meeting it is Reproduced, and this summary cites that deliverable. - Tc: full Allen–Dynes with f1·f2 at μ* = 0.10. McMillan and μ* = 0.13 are for information. μ* = 0.13 is not tabulated in Alexandria; recompute it from λ, ωlog, ω̄2. - The hull is computed under the same settings as the material. Alexandria's own hull is for triage only and never counts. - Dynamic stability: no imaginary mode below −5 cm⁻¹ except acoustic modes at Γ. From M1 on, the value must hold within 10% at the next denser grids, and the lower value counts. - A computed Tc is a proposal for an experiment, not a superconductor.