Stillinger water model

Potential functions based on the sp3-hybrid tetrahedral structure model of water molecules in which two positive and two negative charges are placed at the tetrahedral positions in the molecule have been proposed by Bjerrum 1), Ben-Naim and Stillinger (BNS model) (2), and Stillinger-Rahman (ST2) (3). 

The connection of dipole correlation with angular-momentum correlation cannot be quite so direct for a non-linear molecule. Rahman and Stillinger have published a detailed molecular-dynamics study of a water model containing 216 model molecules in a cube with periodic boundary conditions, at a density of 1 kg dm . The short-time behaviour of the molecules is dominated by librations at 1—2 x 10 Hz. They ve Cole-Cole plots of the electric permittivity estimated by applying an analysis due to Nee and Zwanzig to the computed molecular-correlation function. However, this application is uncertain in view of the... 

MD results for the BNS rigid water model at 641 K (Stillinger and Rahman 1972). MD results for the Carravetta-Clementi potential (Kataoka 1989). 

The rotational relaxation of water molecules is often discussed in terms of angular momentum autocorrelation functions (e g., Stillinger and Rahman 1972 Yoshii et al. 1998). For a flexible water model, a slightly different approach can also be used. In order to separate the various modes of molecular librations (hindered rotations) and intramolecular vibrations, the scheme proposed by Bopp (1986) and Spohr et al. (1988) can be employed. The instantaneous velocities of the two hydrogen atoms of every water molecule in the molecular center-of-mass system are projected onto the instantaneous unit vectors i) in the direction of the corresponding OH bond (ui and U2) ... 

Figure 2. Stillinger-David water model showing formal charges, induced point dipole on oxygen, equilibrium geometry, overall dipole moment, and dissociation energy.

Figure 2(a) 3 charge model for N2 (6 charge distribution for Rahman and Stillinger water (jj 7.03 x... 

Owing to its important role in life, water is a natural choice for polarizable force field development. After the polarizable (and dissociable) water model of Stillinger and David, " more than a dozen polarizable water models have been reported. " ... 

TIP4P, TIP5P SPC models, SPC and SPC/E rigid Stillinger and Rahman model, ST2 and the flexible three-centered water model, F3C. " ... 

Stillinger FH, David CW (1978) Polarization model for water and its ionic dissociation products. J Chem Phys 69(4) 1473... 

One of the most important developments in the theory of water is the invention of a realistic effective intermolecular pair potential. Although others had made similar suggestions earlier 59>, it is Stillinger and co-workers 60> who have shown, with the aid of molecular dynamics calculations 3>, how satisfactory such a potential can be. The availability of a water-water potential drastically reduces the scope for parameterization in model based theories, and permits investigation of such concepts as "broken hydrogen bond. We shall frequently have occasion to call upon its properties in the following discussion. 

Two cell models of water have been reported. Weissman and Blum 63> considered the motion of a water molecule in a cell generated by an expanded but perfect ice lattice. Weres and Rice 64> developed a much more detailed model, based on a more sophisticated description of the cell and a good, nonparametric water-water interaction namely the Ben-Naim-Stillinger potential 60>. The major features of the WR model are the following ... 

The potential model for water used in our work is taken from the work of Stillinger and David (8) (SD) as modified by Halley and co-workers (9) (HRR). Models for water that are capable of hetero-lytic dissociation into ions OH and H+ could take two different approaches. Probably the best approach, promising but not yet... 

Stillinger (1980) suggested that disconnected icebergs should not be present, but that a more likely model is that of a random, three-dimensional network of hydrogen bonds, rather than long-lived clusters of molecules. Such networks of hydrogen-bonded water molecules and clusters are present when hydrates form or dissociate. These clusters are discussed relative to nucleation of hydrates in the following chapter. 

The hydrogen-bonded network picture of Rahman and Stillinger (1973, 1974) is the most favored model. Stillinger (1980) also described water as a macroscopically connected (three dimensional) random... 

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