The relationship between the formation of clusters containing tetrahedral molecules and the dynamic and thermodynamic anomalies of cooled TIP4P/2005 water

摘要

Molecular dynamics simulations have been used to cool the simple liquid TPI4P/2005 water at 350 K to 100 K. We find that structural changes of the system cause dynamic and thermodynamic anomalies. A strong increase in the number of tetrahedral oxygen atoms and combinations of these atoms lead to water's a phase transition from a simple liquid form into a supercooled one or ice at T (I) = 200 K. In the initial stage, small patches containing tetrahedral oxygen atoms connect together to yield large clusters. The rapid drop in the number of clusters and the speedy growth in the size of the largest cluster lead to water's exhibiting anomalously dynamic behaviors at temperatures around 279 K. Our results also show that water is very stable in its supercooled or ice state, exhibiting no change in the mean squared displacement, light oscillation in the number of the clusters and in the size of the largest cluster.