Interpretation of the unusual behavior of H2O and D2O at low temperature: Are concepts of percolation relevant to the “puzzle of liquid water”?

This talk will summarize the present status of an ongoing research program designed to answer the question posed in the title. Since a snapshot of liquid water with a subpicosecond shutter speed reveals that this system (a hydrogen-bonded liquid) is above its percolation threshold, it is tempting to imagine that connectivity concepts of the sort encompassed in percolation theory may prove useful. We find that the traditional approach of random-bond percolation theory-developed to describe the onset of gelation - is not sufficient, since water is well above its gelation threshold. Hence we develop a new correlated-site percolation model, whose predictions are found to be in quantitative agreement with molecular dynamics calculations and in qualitative agreement with a wide range of experimental data on low-temperature water.