  Despite the modern level of development of computational chemistry methods
and techno-logical progress, fast and accurate determination of solvation free
energy remains a huge problem for physical chemists. In this paper, we describe
two computational schemes that can potentially solve this problem. We consider
systems of poorly soluble drug compounds in supercritical carbon dioxide.
Considering that the biggest contribution among all inter-molecular
interactions is made by van der Waals interactions, we model solute and solvent
particles as coarse-grained ones interacting via the effective Lennard-Jones
potential. The first proposed approach is based on the classical density
functional theory and the second one relies on molecular dynamics simulation of
the Lennard-Jones fluid. Sacrificing the precision of the molecular structure
description while capturing the phase behavior of the fluid with sufficient
accuracy, we propose computationally advantageous paths to obtaining the
solvation free energy values with the accuracy satisfactory for engineering
applications. The agreement reached between the results of such coarse-graining
models and the experimental data indicates that the use of the all-atom
molecular dynamic simulations for the studied systems seems to be excessive.
