Comment on "Spontaneous liquid-liquid phase separation of water" by T. Yagasaki, M. Matsumoto and H. Tanaka, Phys. Rev. E 89, 020301 (2014)

Yagasaki et al. present results from a molecular dynamics trajectory illustrating coarsening of ice, which they interpret as evidence of transient coexistence between two distinct supercooled phases of liquid water. We point out that neither two distinct liquids nor criticality are demonstrated in this simulation study. Instead, the illustrated trajectory is consistent with coarsening behaviors analyzed and predicted in earlier works by others.