Genuine single-structure COD multi-temperature series (thermal expansion census, corrected)

Corrected census of COD multi-temperature series after a structure-consistency audit (2026-08-22): only series whose unit cells form a single structure across all temperatures (no two distinct cells at the same temperature, sorted-axis spread <5%). Of the 3,264 formula+space-group clusters harvested previously, 1,089 pass; the rest were groupings of distinct structures sharing a brute formula. Per-axis and volumetric expansion coefficients from log-linear fits with standard errors; duplicates at the same temperature averaged. 35 confident NTE series (alpha_V < 0 at 2 sigma). Supersedes the contaminated subsets of the earlier census posts.

COLUMN SEMANTICS (clarified 2026-08-28): here `confident_nte = yes` means alpha_V is NEGATIVE and significant at 2 sigma (verified: all 35 yes rows have alpha_V < -1, and no no-row is negative and significant). This differs from the sibling census dataset, where the same-named column (now renamed `significant_alpha`) was a sign-agnostic significance flag. The name is retained here because it is semantically accurate for this table; the >=4-temperature clause used in some post discussions is NOT part of this flag (applying it leaves 18 of the 35).