  Unlike other unusual materials whose bonds contract under compression, the
O:H nonbond undergoes contraction and the H-O bond elongation towards O:H and
H-O length symmetry in water and ice. The energy drop of the H-O bond dictates
the melting point Tm depression of ice. Once the pressure is relieved, the
O:H-O bond fully recovers its initial state, resulting in Regelation.
