Models of intermolecular interactions

Section IX. We discuss a principally new way, initiated only recently [12, 12a], of modeling of intermolecular interactions. Namely, we start from a very simplified molecular structure of liquid water depicted in Fig. 2e. An approximate solution of the equations of motion of a single polar molecule is found. The key aspect of this approach is that the H-bond resembles a... 

In Section VII we have applied a phenomenological approach in point of the forms of the potential wells characteristic for water. Now we shall consider a principally another way of modelling of intermolecular interactions pertinent to vibration of the H-bonded molecules. Recently [10, 12, 12a], a preliminary studies of the molecular dynamics was undertaken based on some picture (although very crude) of the molecular structure of water. We shall here briefly represent these results, namely ... 

Structural data are the most important ones for our purpose here. As discussed in section 4.1 the additive model of intermolecular interactions fails in the case of... 

Johnson ER, Becke AD (2006) A post-Hartree-Eock model of intermolecular interactions inclusion of higher-order corrections. J Chem Phys 124 174104 DFTD3 V21. Rev 6 (2011) SG University Muenster... 

Johnson, E. R., and Becke, A. D. (2006). A post-Hartree-Fock model of intermolecular interactions Inclusion of higher-order corrections, / Chem. Phys. 124, p. 174104, doi 10.1063/1.2190220. 

These last are more abundant for water. This solvent, because of its importance and its molecular simplicity, has been the benchmark for many ideas about the description and modeling of intermolecular interactions. Almost all potentials that have been thus far proposed for not extremely flexible molecular component of liquid systems may be found in the literature regarding water. Alternative strategies in the defining number and position of sites, use diffuse instead of point charges, different approaches to model the many-body corrections, flexible potentials, dissociation of the molecule are some features that can be examined by looking at the water potential literature. 

Eqn (3.122) offers the advantage of not being related to a particular model of intermolecular interactions. This equation for == 1 is the basic equation of the new Flory theory. 

The van der Waals gas law can be derived in various ways from an underlying model of intermolecular interactions. The next two sections give a simple derivation. 

Model of Intermolecular Interactions Inclusion of Higher-Order Corrections. 

In realistic models of intermolecular interactions, the force on particle I changes whenever particle I changes its position or whenever another atom with which particle I interacts changes its position. Therefore the motions of all the particles are coupled together, which results in a many-body problem that cannot be solved analytically. Therefore finite difference methods are used to integrate the equations of motion. 

Models of intermolecular interactions from classical to highly correlated... 

Dipole moments per molecule are substantially enhanced in the chain compared to the dipole moments of the isolated molecules for all three model systems. This enhancement arises as a consequence of mutual polarization of interacting molecules. Unless effective pair potentials are used where this change of molecular properties is incorporated additive models of intermolecular interaction fail in the case of hydrogen bonded systems. 

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