Using LigParGen
Extracting a forcefield from LigParGen
An extremely useful tool to obtain forcefield parameters based on OPLS-AA for a multitude of systems is the LigParGen service provided by the Jorgensen group at Yale. This can, in principle, provide you with a full forcefield (including charges) which can be imported into Dissolve. See the information on importing species for more information on how this process works.