Structure of supercooled water: Polarizable BK3 model versus non-polarizable models

Abstract The polarizable BK3 model of water was simulated, using both Monte Carlo and molecular dynamics methods, along isobars p  = 1 and 1000 bar for temperatures ranging from supercritical down to 228.15 K with the focus on details of its structure and changes with temperature. Since overwhelming majority of results for supercooled model water have been obtained for non-polarizable models, in most cases the ST2 one, we also simulated at corresponding conditions this model along with another, and qualitatively different non-polarizable model, TIP4P/Ice for comparison. In addition to commonly used various order parameters to characterize the structure, and a detailed analysis of the spatial distribution function over the first three coordination shells, we also employ a geometric construction based on the Delaunay tessellation, the method independent of any a priori defined quantity. All these analyses aim at an examination to what extent qualitative differences in the models (force fields) affect the observed structure. It is found that in most cases the polarizable BK3 model and TIP4P/Ice water yield very similar structural properties. On the contrary, ST2 water exhibits, in majority cases, even qualitatively different properties and these findings are discussed in detail. The obtained results suggest that any conclusion on the behavior of supercooled water based on the ST2 model should be taken, at least, with caution.