Ice Regelation: Hydrogen-bond extraordinary recoverability and water quasisolid-phase-boundary dispersivity

Regelation, i.e., ice melts under compression and freezes again when the pressure is relieved, remains puzzling since its discovery in 1850's by Faraday. Here we show that hydrogen bond (O:H-O) cooperativity and its extraordinary recoverability resolve this anomaly. The H-O bond and the O:H nonbond possesses each a specific heat ηx(T/ΘDx) whose Debye temperature ΘDx is proportional to its characteristic phonon frequency ωx according to Einstein's relationship. A superposition of the ηx(T/ΘDx) curves for the H-O bond (x=H, ωH~3200 cm(-1)) and the O:H nonbond (x=L, ωL~200 cm(-1), ΘDL=198 K) yields two intersecting temperatures that define the liquid/quasisolid/solid phase boundaries. Compression shortens the O:H nonbond and stiffens its phonon but does the opposite to the H-O bond through O-O Coulomb repulsion, which closes up the intersection temperatures and hence depress the melting temperature of quasisolid ice. Reproduction of the Tm(P) profile clarifies that the H-O bond energy EH determines the Tm with derivative of EH=3.97 eV for bulk water and ice. Oxygen atom always finds bonding partners to retain its sp3-orbital hybridization once the O:H breaks, which ensures O:H-O bond recoverability to its original state once the pressure is relieved.