SPC/E model of water

One of the most convincing tests of the AG relationship appeared in the work of Scala et al.92 for the SPC/E model of water,57 which is known to reproduce many of water s distinctive properties in its super-cooled liquid state qualitatively. In this study, the dynamical quantity used to correlate with the configurational entropy was the self-diffusivity D. Scala et al. computed D via molecular dynamics simulations. The authors calculated the various contributions to the liquid entropy using the methods described above for a wide range of temperature and density [shown in Figure 12(a-c)]. 

We simulated the SPC/E basal ice/water interface with Na+ and Cl- ions at a temperature of 225 K, which was estimated as the melting point for the SPC/E model of water in our previous study of two-phase coexistence [19]. We have used a collection of 2304 rigid water molecules plus a single solute ion in the NVT ensemble. The time step was chosen to be 1.5 fs. 

Computer simulations have over the years contributed to our understanding of the liquid water/vapor interface. A fairly early study by Wilson et al. (1987) used the TIP4P water model with 342 molecules at a rather high temperature, 52 °C. They confirmed the preferred dipole orientation at the surface with the positive end (hydrogen atoms) towards the bulk liquid and considered the interfacial region to extend 0.75 nm into the liquid. However, the calculated surface tension, 132 46 mN m , is nearly twice the experimental value, so that the implementation of the model needed revision. Subsequent work by others improved on this situation. Taylor et al. (1996) used the SPC/E model of water with 526 molecules at several temperatures from —5 to 100 °C (and also with 1,052 molecules at 25 °C) at 0.1 MPa. A main conclusion is... 

Table 10. Lennard-Jones parameters of ions consistent with the SPC/E model of water.

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See also in sourсe #XX -- [ ]

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