[gmx-users] PME question

[Erik Lindahl]

Hank deHaan wrote:

>Thanks very much for your reply,
>it helps to clarify the situation greatly
>
>Any chance of elaborating on the strange effects
>of charges moving across box boundaries?
>

Well, imagine you have a charge -1 in the center of the box, and +1 next 
to one of the box sides. This will give you a net dipole
in the system. Now, if the +1 charge moves across the box boundary and 
reappears on the other side the dipole will suddenly have
the opposite direction after a discrete instantaneous jump.

Ideally, you should use a box that is large enough so you don't have to 
consider effects on the scale of the box of course....

Cheers,

Erik