H–O Bond Dynamics: Length, Energy, and Flexibility under Perturbation

This study reveals the dynamic flexibility of the intramolecular H–O bond under perturbations (pressure, temperature, coordination, and electric field), challenging its conventional rigidity and proton dynamic mobiity. By integrating bond nature index (m) analysis, tight-binding theory, and perturbation-resolved phonon spectroscopy (PRS), we quantify perturbation-driven changes in H–O bond length, energy, vibrational stiffness, O 1s core-level energy, and O:H nonbonding distance. A spectroscopic database correlates H–O bond relaxation and energy transfer in water, ice, hydroxides, and extraterrestrial systems (e.g., lunar water), capturing anomalies such as bond elongation under compression and contraction upon heating. These results redefine classical two-body hydrogen bonding models by emphasizing cooperative O:↔:O coupling and bond adaptability. Our approach enables direct extraction of bond parameters from spectral data, advancing predictive models for phase behavior and energy dynamics in hydrogen-bonded networks across chemistry, materials science, and planetary research.