A recommended method for calculating liquid-phase free energies is SMD . It is a continuum method but takes into account contributions from the first solvation shell via paremetrization. This model, like its authors' other SM x methods, includes a term for non-electrostatic effects due to cavity formation, dispersion interactions, and solvent structure. The contribution is dependent upon the solvent-accessible surface area (SASA) of each solute atom. The main feature distinguishing SMD from the other SM x methods is that it utilizes a continuous charge density of the solute, rather than a discrete representation. In the Gaussian computational chemistry program , the method is combined with the polarizable continuum method (PCM) for single-point energy calculations on a solute in a solvent. However, it can be used with other algorithms such as COSMO and COSab implemented in other software packages.