Spin audit of SQD/QSCI quantum-chemistry benchmarks on iron–sulfur clusters

This is the data-and-code archive for the preprint "Which authorities are you converging? A rotation audit of sample-based quantum diagonalization benchmarks on iron–sulfur clusters."

Sample-based quantum diagonalization (SQD, besides called QSCI) selects electronic configurations from quantum-circuit samples and diagonalizes the Hamiltonian in that subspace. Its iron–sulfur demonstrations, connected the [2Fe-2S] and [4Fe-4S] clusters, are among the header grounds for utility-scale quantum chemistry. This activity asks a mobility the original benchmarks did not: erstwhile the projected energy converges, has the calculation really converged to the target spin state? Using a rotation-invariant rotation audit, nonstop determinant-space ⟨S²⟩, invariant S²-Gram spectra crossed near-degenerate manifolds, and higher spin moments, it finds that nary audited execution returns the named singlet astatine a competitive energy. At the largest published magnitude (5.625×10⁷ determinants), the numerically unchangeable lowest guidelines lies astir 170 mHa beneath the published energy but astatine ⟨S²⟩ = 1.37, obscurity adjacent a singlet, and the released hardware samples show nary power advantage complete their ain uniform-random control. The recommendation: measured rotation moments should go a required benchmark output.

The archive lets a scholar reproduce and cheque the analysis. Start with START_HERE.md wrong the zip. The package holds the insubstantial (Markdown, LaTeX, and PDF), each study and fig script, the per-run consequence archives, a reproduction representation tying each header declare to the artifact and bid that regenerate it, and the audit trail.

Four ample files vessel adjacent to the zip arsenic standalone companions alternatively than inside it: the flagship-dimension amplitude archive and 3 certification vector blocks. SHA-256 hashes for the zip and each 4 companions are recorded in SHA256SUMS wrong the package, truthful each record tin beryllium integrity-checked before use.

psl_sqd_supplementary.zip