[gmx-users] Charge groups, PME and ions

[Andreas Kring]

Hello all.

I have read the manual and searched the archives, but I am still a 
little confused so here goes:

I am going to perform an MD simulation of a molecule consisting of 38 
atoms and with a total charge of -4e (water as the solvent). For this 
molecule it is not possible to make charge groups with a total charge of 
zero (or and integer number).

Is this best solved by using a separate charge group for each atom?...
and is this allowed since the charge of such a charge group is not zero?

According to the manual, the charge groups are used to make neighbor 
lists... but these are only important with respect to the computational 
speed as long as PME is used to deal with electrostatic interactions? Or 
have I misunderstood this?

/Andreas