Solvation

When you run a regular Jaguar calculation, the molecule is being calculated in the gas phase at absolute zero. If you want to know the solution phase energy, Jaguar can "embed" your molecule in a dielectric constant according to the solvent and calculate the energy due to solvation. This method is referred to as using an implicit solvent.

In most cases of interest to our research group, the geometry of the molecule does not change significantly between the gas phase and the solution phase. If this is the case, you do not need to re-optimize the geometry of the molecule in the solution. Even if there might be changes, it is more efficient to calculate the geometry of several conformers in the gas phase and then simply calculate the solvation energy for each of these conformers.

Here's what you do after your gas phase calculation is complete.
1. Copy the .01.in file to a new input file. You will then make the following changes to the &gen section of your new input file (call it filename_solv.in or something like that)
2. Remove the keyword igeopt=1 (since you don't need to optimize the geometry further, and it would take a l-o-n-g time if you did)
3. Add the keyword isolv=2
4. If your solvent is not water, add the keywords epsout=x.x and radprb=y.y where x.x and y.y are the dielectric constant and probe radius respectively for the solvent.
5. Run the Jaguar calculation.