GQR–VIII: Coherent Gating and Multi-Particle Tunnelling in the PSII Oxygen-Evolving Complex

The Gated Quantum Resonator (GQR) framework models reactive coordinates as coupled vibronic–electronic resonators controlled by a finite gate alphabet. Applied to the Photosystem II oxygen-evolving complex (OEC), GQR maps verified XFEL geometries onto a graph Hamiltonian with gate-conditioned couplings. We demonstrate: (i) species-selective resonance combs that separate electron and proton flux topologies; (ii) hydration-mediated shield softening that sustains coherence; and (iii) a geometry-to-graph workflow producing interpretable tunnelling movies. Catalysis emerges as a managed decoherence between a fast (3–5 fs) electronic band and a slower (20–30 fs) water vibronic band. The framework reinterprets the anomalous S2-like coherence of the 8F4C S3 structure 1 as a dehydration-induced artifact. GQR delivers order-of-magnitude computational savings relative to MD/QM while offering a mechanistic bridge between structure and quantum dynamics. This study extends the author’s Gated Quantum Resonator (GQR) program (I–VII, ChemRxiv 2025), advancing its unified framework for coherence, tunnelling, and catalysis through a full application to Photosystem II OEC dynamics. Significance The Gated Quantum Resonator (GQR) replaces heavy MD/QM sampling with a gate-driven, geometry-faithful framework for coherent charge and proton transport. Applied to the PSII OEC, it transforms verified atomic coordinates into a controllable graph Hamiltonian, generating tunnelling movies that preserve the physical levers—distance decay, spin selectivity, hydration, and shielding—without exascale computation. Catalysis appears as a coherence–decoherence transition linking the well-characterized Kok states 2–4. The framework’s economy (103–106 -fold savings) accelerates catalyst design for green hydrogen and points toward PSII-inspired materials for quantum devices.