P A. Netz, Francis W. Starr, H E. Stanley, M C. Barbosa
We present the results of molecular dynamics simulations of the extended simple point charge (SPC/E) model of water to investigate the thermodynamic and dynamic properties of stretched and supercooled water. We locate the liquid-gas spinodal, and confirm that the spinodal pressure increases monotonically with T, supporting thermodynamic scenarios for the phase behavior of supercooled water involving a non-reentrant spinodal. The dynamics at negative pressure show a minimum in the diffusion constant D when the density is decreased at constant temperature, complementary to the known maximum of D at higher pressures. We locate the loci of minima of D relative to the spinodal, showing that the locus is inside the thermodynamically metastable regions of the phase-diagram. These dynamical results reflect the initial enhancement and subsequent breakdown of the tetrahedral structure and of the hydrogen bond network as the density decreases.
Physical Review E (Statistical, Nonlinear, and Soft Matter Physics)
diffusion minimum, molecular dynamics, negative pressure, simulations, spinodal, water