O:H–O bond segmental length cooperative relaxation. O—O repulsion dislocates O ions in the same direction by different amounts (insets) under (a) mechanical compression, cooling of (b) liquid and (c) quasisolid (QS) phase (in units of °C), and (d) undercoordination by reducing the (H₂O)_N size from N = 6 to 2. Arrows denote the master pieces and their relaxation directions. The H–O bond always relaxes less than the O:H and both of them relax contrastingly in their curvatures and slopes, irrespective of the applied stimulus or the structural order because of the O–O Coulomb repulsive coupling (reprinted with permission from Ref. [63]).