The Scretching Quantum Chain (SQC): A Deterministic Quantum–Spectroscopic Framework for Reference-Grade Optical and Electromagnetic Modeling Description: The Scretching Quantum Chain (SQC) is a deterministic quantum–atomic framework that enforces exact internal consistency among fundamental spectroscopic quantities, including oscillator strength fff, transition dipole moment ∣μ∣2|\mu|^2∣μ∣2, Einstein coefficients A21,B21,B12A_{21}, B_{21}, B_{12}A21,B21,B12, and related radiative parameters. Derived directly from first-principles quantum electrodynamics (QED), the SQC is formulated as a closed computational chain in which all quantities are exact linear multiples of a single canonical driver variable under fixed transition conditions. Unlike conventional regression-based or empirically tuned spectroscopic models, the SQC eliminates statistical fitting at the core physics level. All mappings are identity-level relations with analytically fixed slopes, zero intercepts, and forced coefficients of determination R2=1.000R^2 = 1.000R2=1.000. Any deviation from identity closure therefore signals a unit mismatch, convention inconsistency, or data-quality issue rather than model failure. In this work, the SQC is validated using critically evaluated NIST atomic data for Hydrogen H I Balmer fine-structure channels and selected Neon I transitions. Hydrogen serves as a predictive benchmark, demonstrating reference-grade agreement between reconstructed and tabulated Einstein coefficients, while Neon provides a multi-electron stress test illustrating the SQC’s diagnostic capability in identifying multiplet averaging and convention-dependent oscillator-strength definitions. The SQC is designed to function as the quantum-atomic counterpart to the Maxwell–Scretching Chain, which deterministically links macroscopic optical observables (molar absorptivity, absorption coefficient, extinction coefficient, dielectric loss) to oscillator strength in bulk materials and biomolecular systems. Together, the two frameworks form a unified, multiscale pipeline connecting classical electromagnetism to quantum transition physics without empirical fitting. This work complements and extends the Maxwell–Scretching framework introduced in: Scretching, D. C. (2025a). The Maxwell–Scretching Equations and Their Quantitative Link to UV–Visible Spectroscopy of DNA Nucleobases (Version 1.0). Zenodo. https://doi.org/10.5281/zenodo.17766185 The SQC is intended as a reference-grade verification backbone for spectroscopy databases, laboratory instrument calibration, computational spectroscopy software, and cross-disciplinary optical modeling in physics, chemistry, and computational biology. Keywords:quantum spectroscopy; oscillator strength; Einstein coefficients; deterministic regression; atomic physics; reproducibility; NIST; Maxwell–Scretching framework