Interdisciplinary Applied Mathematics

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74.539 J/mol/K

Thermal conductivity

0.610 W/m/K

Dynamic viscosity

0.8909 mPa-s

jUnless mentioned otherwise, all the properties are reported at 25° C.

may not    coincide    with    one    or    more    of the    charged    sites.    Generally,    each

model is developed to match well a certain set of physical structures or parameters (e.g., the density anomaly, radial distribution function, or other critical parameters). A discussion of the various atomistic models for water is presented next.

11.1.1 Atomistic Models

There are a number of atomistic models for water, and a description of the majority of the models can be found in (Chaplin, 2004). In this section we summarize only the most commonly used models for water.

The SSD Model

The water molecule in the soft sticky dipole (SSD) model is treated as a Lennard-Jones sphere with an embedded point dipole plus a tetrahedral “sticky” potential, all situated at the molecular center of mass (M) located on the H-O-H bisector at 0.0654 A from the oxygen toward the hydrogens (see Figure 11.2). The geometry of the water molecule used in this model is similar to that of any three-site model (e.g., TIP3P). The O-H length (i.e. гон) is 0.9572 A and the H-O-H angle (i.e. 0HOH) is 104.52°. The H-M-H angle is 109.47°. The center of mass is the only interaction site of this model (Liu and Ichiye, 1996).

In the SSD model, the total interaction potential energy between two water molecules i and j is given by (Liu and Ichiye, 1996)

V ■ = VLJ (г

VIJ V j V г-

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