Computation of Solvent Effects

If the purpose of a calculation is to probe the inherent properties of a molecule as a thing in itself, or of a phenomenon centered on isolated molecules, then we do not want the complication of solvent. For example, a theoretically oriented study of the geometry and electronic structure of a novel hydrocarbon, e.g. pyramidane [6], or of the relative importance of diatropic and paratropic ring currents [7], properly examines unencumbered molecules. On the other hand, if we wish, say, to calculate from first principles the pZa of acids in water, we must calculate the relevant free energies in water [8]. Noteworthy too is the fact that solvation, in contrast to gas phase treatments, is somewhat akin to molecules in bulk, in crystals [9]. Here a molecule is solvated by its neighbors in a lattice, although the participants have a much more limited range of motion than in solution. Rates, equilibria, and molecular conformations are all affected by solvation. Bachrach has written a concise review of the computation of solvent effects with numerous apposite references [10]. 

Here we summarize the results of a research we have published on Journal of American Chemical Society on the computation of solvent effects on N nuclear shielding of diazines within the PCM-IEF framework. 

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