atomref-proatoms: spherical atomic and ionic reference densities

atomref-proatoms is a versioned dataset and accompanying Python toolkit for spherical atomic and ionic reference electron densities. Version 2.0.0 provides 501 curated atomic-state records and 1,289 generated dataset-state profiles across four all-electron scalar-relativistic basis branches. The state layer covers neutral atoms, cations, curated monoanions, and explicitly formal anion references under a documented provenance and selection policy. Open-shell proatoms are generated using self-consistent spherical fractional occupations. Electrons in partially occupied angular-momentum shells are distributed over complete magnetic manifolds during the self-consistent-field cycle, rather than being angularly averaged only after an anisotropic open-shell calculation. The production protocol uses PBE0, spin-free one-electron exact two-component relativity, unrestricted spherical SCF, pure Gaussian basis functions, a fixed logarithmic radial grid, and independent numerical validation of electron counts, angular sphericity, radial tails, and density-cutoff radii. The primary reference branches are x2c-QZVPall for H–Rn and dyall-v4z for H–Lr. The x2c-QZVPall-s and dyall-av4z branches provide explicit basis-sensitivity diagnostics for neutral and anionic density tails. The archive contains radial electron-density profiles, density-cutoff radii, per-state QA tables and summaries, basis-comparison data, curated state and basis metadata, frozen basis inputs and provenance, 931 Multiwfn .rad files, 86 neutral-atom PROAIM .wfn files, documentation, examples, validation scripts, and the source of the generator toolkit. The profiles are intended as documented proatomic reference gauges for stockholder and Hirshfeld-like partitioning, promolecular and deformation-density calculations, atomic-radius models, real-space descriptors, and compatible Multiwfn workflows. Formal anion rows are computational reference conventions and are not claims that the corresponding isolated atomic anions are physically stable. Different basis sets, state policies, relativistic treatments, core conventions, or density models should be treated as distinct reference gauges.