I've just found this paper (J. Chem. Phys. 141, 174106 (2014)) that deals with the translational and rotational entropies in solution. The method is promising but, unfortunately, requires a modification in the frequency calculation that is not readily available on most quantum chemistry packages.
As such, my question is which methods explicitly calculate solvation contributions to free energies and how do they compare?
They naturally have something to do with a polarizable continuum (J. Phys. Chem. A 1998, 102, 11, 1995-2001), but which methods go beyond pure electrostatic/cavity/dispersion energies and deal with free energy in terms of entropies and enthalpies (as in the rigid rotor-harmonic oscillator approximation)? (I would rather avoid purely parameterized corrections as in, e.g., J. Phys. Chem. B 2009, 113, 18, 6378-6396.)
The problem of entropy
In terms of free energy contributions, one particularly significant contribution is entropy. Are there any readily available methods/theories for the rotational and translational contributions to enthalpy and entropy of solutes?
I am particularly interested in the fact that current successful methods (SMD, PCM, etc.) seem to adjust electronic energies using free energy terms, such as CPCM (which explicitly uses an equation derived by Pierotti from the hard-sphere theory for calculating the cavity free energy, J. Phys. Chem. A 1998, 102, 11, 1995-2001), or SMD (which uses purely parameterized terms that certainly include entropic contributions). As such, their temperature dependence likely wrong (or am I missing something?). This has been addressed in recent publications to some extent, such as in Catal. Sci. Technol., 2019,9, 5433-5440 and ACS Catal. 2019, 9, 8, 6803–6813.