Weighteddensity functionals for cavity formation and dispersion energies in continuum solvation models
Abstract
Continuum solvation models enable efficient first principles calculations of chemical reactions in solution, but require extensive parametrization and fitting for each solvent and class of solute systems. Here, we examine the assumptions of continuum solvation models in detail and replace empirical terms with physical models in order to construct a minimallyempirical solvation model. Specifically, we derive solvent radii from the nonlocal dielectric response of the solvent from ab initio calculations, construct a closedform and parameterfree weighteddensity approximation for the free energy of the cavity formation, and employ a pairpotential approximation for the dispersion energy. We show that the resulting model with a single solventindependent parameter: the electron density threshold (n_{c}), and a single solventdependent parameter: the dispersion scale factor (s_{6}), reproduces solvation energies of organic molecules in water, chloroform, and carbon tetrachloride with RMS errors of 1.1, 0.6 and 0.5 kcal/mol, respectively. We additionally show that fitting the solventdependent s_{6} parameter to the solvation energy of a single nonpolar molecule does not substantially increase these errors. Parametrization of this model for other solvents, therefore, requires minimal effort and is possible without extensive databases of experimental solvation free energies.
 Publication:

Journal of Chemical Physics
 Pub Date:
 October 2014
 DOI:
 10.1063/1.4896827
 arXiv:
 arXiv:1407.4011
 Bibcode:
 2014JChPh.141m4105S
 Keywords:

 Physics  Chemical Physics
 EPrint:
 J. Chem. Phys. 141, 134105 (2014)