Regelation: why does ice melt under pressure?

TL;DR

This paper explains how pressure-induced melting and refreezing of ice, known as Regelation, is driven by bond length changes in water molecules, particularly the H-O bond energy drop.

Contribution

It reveals the microscopic bond mechanisms behind Regelation, linking bond length changes to pressure and temperature effects in ice.

Findings

H-O bond elongates while O:H contracts under pressure

H-O bond energy drop causes melting point depression

Ice fully recovers its structure after pressure is released

Abstract

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.