v0.7.0 — Löwdin's Compass — periodic SCF correctness + linear-dependence program Headline deliverables: * **Periodic SCF gauge fix.** Translation invariance restored to FFT precision (~5e-6 Ha) on H₂/STO-3G/L=30. Molecular-limit energy improved from -1.114878 → -1.115774 Ha (within 0.94 mHa of the molecular reference -1.116714 Ha). Dense-ionic crystals (LiH conventional rocksalt) iter-1 over-binding dropped from -1647 Ha to physical -50 Ha — the V_ne dispatch + Madelung reconciliation closed the long-standing gauge inconsistency between the FFT-Poisson J build and the bare-libint V_ne sum. * **Linear-dependence + screening program.** 10 public APIs across 5 new modules: scf_preflight_overlap_check, eigs_preflight, optimize_truncation (default-ON in all 8 SCF drivers), disambiguate_critical_overlap (CRYSTAL TOLINTEG distinction), make_basis(..., exp_to_discard=...) with full per-primitive drop transparency, canonical / Lehtola pivoted Cholesky / symmetric orthogonalisation methods. * **Active-settings dump** at SCF startup in all 8 periodic drivers for full reproducibility (every overridable knob printed). * **Automated regression suite** (examples/regression/, wave 1). 6/6 molecule cases pass; periodic systems ready for planext. Codename "Löwdin's Compass" honours Per-Olov Löwdin's 1970 canonical- orthogonalisation paper (Adv. Quantum Chem. 5, 185), the conceptual heart of this release's linear-dependence work. References landed in code + docstrings: - Lykos & Schmeising J. Chem. Phys. 35, 288 (1961) - Löwdin Adv. Quantum Chem. 5, 185 (1970) - Peintinger, Vilela Oliveira, Bredow J. Comput. Chem. 34, 451 (2013) - VandeVondele & Hutter J. Chem. Phys. 127, 114105 (2007) - Searle, Bernasconi, Harrison ARCHER eCSE04-16 (2017) - Vilela Oliveira et al J. Comput. Chem. 40, 2364 (2019) - Lehtola J. Chem. Phys. 151, 241102 (2019) - Ye & Berkelbach J. Chem. Theory Comput. 18, 1595 (2022) - CRYSTAL23 manual: EIGS, TOLINTEG, OPTBASIS, basis-design Ch. 17 Co-Authored-By: Claude Opus 4.7 (1M context) <noreply@anthropic.com>