..well, we all know that the charmm FF is not tailored for use in gas phase or even vacuum simulation.
Even so, I would like to ask if someone has significant experience in this field or could give advice which modifications of partial charges have to be made to get a more reasonable model e.g. for ion mobility mass spectrometry experiments.
(I fully agree with all who claim that vacuum simulations are insufficient in order to understand membrane proteins; Nevertheless, it could be helpful to extract some ideas from "cheap" simulations and refine them in subsequent sophisticated/explicit solvent simulations)
David Minde
