The calculation of free energies of solvation as functions of temperature

COMP 369

Adam Chamberlin, chamberlin@chem.umn.edu, Department of Chemistry and Supercomputing Institute, University of Minnesota, 207 Pleasant St. SE, Minneapolis, MN 55455-0431
Implicit (continuum) solvation models have proven particularly useful for predicting free energies of partitioning between different phases (commonly the gas phase and liquid solution). However, the variation of the free energy of solvation as a function of temperature has not typically been addressed with such models. Solvation Model 6 with Temperature dependence (SM6T) is a semiempirical model that has been developed to address this deficiency and it is presently defined for aqueous free energies of solvation of compounds containing H, C, and O over the temperature range 273 K to 373 K. SM6T computes the temperature dependence of the bulk electrostatic contribution to the free energy of solvation using the Generalized Born equation and the temperature dependence of the solvent dielectric constant. The temperature dependencies of first solvation shell effects are modeled using parameterized solvent exposed surface area dependent terms. SM6T predicts the temperature dependence of aqueous free energies of solvation with a root mean squared error of 0.09 kcal/mol over a large database (the error associated with assuming no temperature dependence is 0.65 kcal/mol).