Models Stillinger

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... 

Stillinger F 1973 Structure in aqueous solutions from the standpoint of scaled particle theory J. Solution Chem. 2 141 Widom B 1967 Intermolecular forces and the nature of the liquid state Sc/e/ ce 375 157 Longuet-Higgins H C and Widom B 1964 A rigid sphere model for the melting of argon Mol. Phys. 8 549... 

Stillinger FH (1979) Dynamics and ensemble averages for the polarization models of molecular interactions. J Chem Phys 71(4) 1647... 

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

The lesson, that drastically simple Hamiltonian models are adequate to generate quite realistic fluid properties and hence to understand the structure of fluids, can be reinforced by many other examples. For the present Symposium the most important may be the Stillinger-Rahman series of studies of a BO-level... 

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 characteristic time of this diffusion was estimated by carrying out the molecular dynamic relaxation of the film surface within the limits of the above model at 500°C. In MD calculations, the pair interaction energy between atoms is approximated by the Buckingham pair potential (Zr O, O-O) (see Table 9.4). To describe covalent bonds more correctly, a three-body O-Zr-O term in the Stillinger-Weber form was introduced in addition to the Coulomb term. 

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). 

II. Micellization Model and Ben-Naim-Stillinger Free-Energy Expression... 

Structural models for molten salts have been proposed by several authors Bockris [1-3], Stillinger [4], Zarzycki [5], Janz [6], Kleppa [7], Blander [8], and others. These structural models are based on the older theories of the liquid state, which were applied for molecular liquids, liquified gases, molten metals, etc. Some of these models will be treated in the following. 

Lemberg HL, Stillinger FH (1975) Central force model for liquid water. J Chem Phys 62 1677-1690... 

A simple model, which has been quite successful in solids with the diamond or zinc-blende stmcrnre, was introduced by Stillinger and Weber (Stillinger and Weber, 1985). The first term in the potential is the product of a Lennard-Jones-like pair-wise interaction and a cut-off function smoothly terminating the potential at some distance r. The second term is a multi-variable three-body potential written as a separable product of two radial functions and an angular function ... 

Eor simplicity, however, let s adopt an atomic-level description of the molecular solution. As with the central-force models (Lemberg and Stillinger, 1975), the interactions treated could be sufficiently complicated as to form complex molecules, but we will focus on the interaction contributions to the chemical potentials of atoms. In that case, all = 1, and any quantum mechanical effects on the internal structures of molecules that may be formed will have to be described by the quantum mechanical approximations that are the target here. 

But the size dependence of these results has long been an interest also (Stillinger, 1973). For hard-sphere model solutes, the size dependence is analyzed by introducing... 

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