Solvation lattice model

The randomly occupied lattice model of a polymer solution used in the Rory-Huggins theory is not a good model of a real polymer solution, particularly at low concentration. In reality, such a solution must consist of regions of pure solvent interspersed with locally concentrated domains of solvated polymer. 

Molecular mechanics is a simple technique for scanning the potential energy surface of a molecule, molecular ion, crystal lattice, or solvate. The model is based on chemical and physical principles. The resulting functions are parameterized on the basis of experimental data. That is, the potential energy surface is computed not by thorough theoretical expressions but by using functions whose parameters are derived empiri-... 

Molecular mechanics is a simple technique for scanning the potential energy surface of a molecule, molecular ion, crystal lattice or solvate. The model is based on a set of functions which may or may not be based on chemical and physical principles. These functions are parameterized based on experimental data. That is, the potential energy surface is not computed by fundamental theoretical expressions but by using functions whose parameters are derived empirically by reproducing experimentally observed data. Molecular mechanics then is, similar to a neural network, completely dependent on the facts that it has been taught. The quality of results to be obtained depends on the choice of the experimental data used for the parameterization. Clearly, the choice of potential energy functions is also of some importance. The most common model used is loosely derived from... 

The influence of the interaction in binary solvents on AG r ions was analyzed by Y. Marcus [261], who assumed a quasi-lattice model for the electrolyte in such solutions. Free energies of transfer of various ions were collected and discussed [75, 76]. Ion solvation including mixed solvent media has been reviewed by several authors [45, 76, 262-265]. 

Papazyan, A. and Warshel, A. (1997). Continuum and dipole-lattice models of solvation. J. Phys. Chem. B, 101, 11254-11264. 

Koga et al. (2002) found a linear correlation between the PMF and the solvation Gibbs energy in a lattice model of aqueous solutions. As we have demonstrated above, such a correlation does not exist in general. 

Girault and Schiffrin [4] proposed an alternative model, which questioned the concept of the ion-free inner layer at the ITIES. They suggested that the interfacial region is not molecularly sharp, but consist of a mixed solvent region with a continuous change in the solvent properties [Fig. 1(b)]. Interfacial solvent mixing should lead to the mixed solvation of ions at the ITIES, which influences the surface excess of water [4]. Existence of the mixed solvent layer has been supported by theoretical calculations for the lattice-gas model of the liquid-liquid interface [23], which suggest that the thickness of this layer depends on the miscibility of the two solvents [23]. However, for solvents of experimental interest, the interfacial thickness approaches the sum of solvent radii, which is comparable with the inner-layer thickness in the MVN model. 

The fact that only naked molecules are refined is based on the problem that for crystal lattices at least 27 unit cells would have to be included (with at least one unit per cell, including counter ions and solvents of crystallization), and in solution at least 200 molecules of water must be refined in the solvent sheath interacting with the compound to be modeled. Since CPU time f(m2), where m is the number of nuclei, the time required for a single optimization cycle increases dramatically under these conditions. Even more importantly, the initial configuration of the molecule and its environment is not easy to predict since the intermolecular contacts (crystal lattice, ion-pairing and solvation) of a compound to be modeled are not known beforehand. Thus, inclusion of environmental effects in modeling studies has necessitated the use of some severe approximations176-781. 

A wide variety models have been proposed to evaluate these intermolecular contributions to the relaxation energy, including ab initio models for hydrated electrons (33) and hydrated ions (34), microscopic models based on dipolar lattices (35), and dielectric models ranging from the classic Bom model of solvation to its more modern extensions ( , ). The model which... 

---