Dear All,

Afew days ago, I tried to compare the molecular sizes between benzene and proton ion.

For that purporse, I draw a proton atom and typed the force field of the proton atom as a proton ion using COMPASS.

At that time, I found that there is no difference in the molecular size between proton ion (H+) and proton atom (H) with COMPASS forcefield.

And I thought the reason is MD doesn't deal with the caculation at electronic level.

Accordingly, I would like to carry out this simulation using QM with DMol module.

But, I don't know how to draw a proton ion in DMol.

Of course, I can draw a proton atom as mentioned above but after then I cannot change this to proton ion.

Please, help me...