Atomistic simulation of water and ice under compression and shear

Recent gas gun experiments have succeeded in using pressure-shear impact to compress water and probe the resulting phase transition and water/ice mixture. These experiments show signatures of ice solidification via sample strength inferred from back surface velocimetry measurements. Here, we use molecular dynamics simulations to directly investigate the behavior of water and ice VII under these conditions. We use molecular dynamics and both classical and machine learned potentials for water to investigate phase stability for both water (H2O) and heavy water (D2O). We are particularly interested in defining the phase boundaries and kinetics between ice VII, the ice VII plastic phase and the meltline. In the ice VII plastic phase water molecules maintain lattice order, but lose rotational order. We further introduce shear piston boundary conditions to model the atomistic response of water, ice, and mixed water/ice systems.

Sandia National Laboratories is a multimission laboratory managed and operated by National Technology & Engineering Solutions of Sandia, LLC, a wholly owned subsidiary of Honeywell International Inc., for the U.S. Department of Energy’s National Nuclear Security Administration under contract DE-NA0003525. This work describes objective technical results and analysis. Ay subjective views or opinions that might be expressed in the work do not necessarily represent the views of the U.S. Dept. of Energy or the United States Government.