Liquid-liquid phase transition in water

Water shows anomalies different from most of other materials. Different sceniaros have been proposed to explain water anomalies, among which the liquid-liquid phase transition (LLPT) is the most discussed one. It attributes water anomalies to the existence of a hypothesized liquid-liquid critical point (LLCP) buried deep in the supercooled region. We briefly review the recent experimental and theoretical progresses on the study of the LLPT in water. These studies include the discussion on the existence of the first order LLPT in supercooled water and the detection of liquid-liquid critical point. Simulational results of different water models for LLPT and the experimental evidence in confined water are also discussed.