Pressure-induced transformations in glassy water: A computer simulation study using the TIP4P/2005 model

Abstract

We study the pressure-induced transformations between low-density amorphous (LDA) and high-density amorphous (HDA) ice by performing out-of-equilibrium molecular dynamics (MD) simulations. We employ the TIP4P/2005 water model and show that this model reproduces qualitatively the LDA-HDA transformations observed experimentally. Specifically, the TIP4P/2005 model reproduces remarkably well the (i) structure (OO, OH, and HH radial distribution functions) and (ii) densities of LDA and HDA at P = 0.1 MPa and T = 80 K, as well as (iii) the qualitative behavior of ρ(P) during compression-induced LDA-to-HDA and decompression-induced HDA-to-LDA transformations. At the rates explored, the HDA-to-LDA transformation is less pronounced than in experiments. By studying the LDA-HDA transformations for a broad range of compression/decompression temperatures, we construct a "P-T phase diagram" for glassy water that is consistent with experiments and remarkably similar to that reported previously for ST2 water. This phase diagram is not inconsistent with the possibility of TIP4P/2005 water exhibiting a liquid-liquid phase transition at low temperatures. A comparison with previous MD simulation studies of SPC/E and ST2 water as well as experiments indicates that, overall, the TIP4P/2005 model performs better than the SPC/E and ST2 models. The effects of cooling and compression rates as well as aging on our MD simulations results are also discussed. The MD results are qualitatively robust under variations of cooling/compression rates (accessible in simulations) and are not affected by aging the hyperquenched glass for at least 1 μs. A byproduct of this work is the calculation of TIP4P/2005 water's diffusion coefficient D(T) at P = 0.1 MPa. It is found that, for T ≥ 210 K, D(T) ≈ (T - T(MCT))(-γ) as predicted by mode coupling theory and in agreement with experiments. For TIP4P/2005 water, T(MCT) = 209 K and γ = 2.14, very close to the corresponding experimental values T(MCT) = 221 K and γ = 2.2.

Glass polymorphism and liquid–liquid phase transition in aqueous solutions: experiments and computer simulations

“…Here, computer simulations typically employ compression and/or cooling rates that are several orders of magnitude larger than the ones accessible in experiments. [114][115][116][117][118] As shown in Fig. 2a, at these rates experiments show that indeed, isobaric cooling yields either LDA or HDA.…”

“…78,300,301,305,306 Jagla-like pair potentials can also exhibit pressure-induced amorphization of low-density crystals and two glass transition temperatures, [307][308][309] consistent with experiments 83,105,106 and computer simulations of fullatomistic water models. 115,159,166,167,258 However, contrary to the case of full-atomistic water models, reported Jagla-like potentials exhibit an LLPT line with positive, null, or mildy negative slope in the p-T plane (Fig. 14b), while full-atomistic models only show a negatively sloped LLCP line.…”

“…However, this pressure-induced transformation is ten times broader than in pure water, 164 covering a p-interval of E1.5 GPa. For comparison, MD simulations of pure water during the LDA -HDA transformation at similar conditions show that the glass-glass transformation expands over a p-range of only 0.1-0.3 GPa 115,117 or even less. 166,167 The smoothness and small density change in the HDA-LiCl -VHDA-LiCl transformation, relative to the LDA -HDA firstorder like transition in pure water, supports the view where the reported glass-glass transformation in LiCl aqueous solutions with R = 6 is not related to the LLPT between LDL and HDL in pure water.…”

On the time required to freeze water

“…The value of T MCT for TIP4P/ICE is about 12 K above that obtained for TIP4P/2005. 111 For temperatures below 230 K the results are better described by an Arrhenius expression D = D * exp(−E a /(RT)). This change in the variation of D with temperature is sometimes denoted as the fragile-strong transition.…”

“…112 For TIP4P/ICE this change seems to be located at 230 K. The fragile to strong transition for supercooled water for TIP4P/2005 has been studied in detail recently by de Marzio et al 94 and by Wong, Jahn, and Giovambattista. 111 The parameters of the fit for D of TIP4P/ICE (both for temperatures above 230 K and for temperatures below) are shown in the inset of Fig. 5.…”