[gmx-users] Walls and PME for long range electrostatics
miessen at physik.hu-berlin.de
Wed Jul 12 15:11:11 CEST 2017
I am simulating a Au(111) slab with explicit electrons inside (included
as a "free electron gas"). The gold atoms are frozen, the electrons are
free but confined inside the slab by a more repulsive pair interaction
with the Au-surface atoms. This works fine and simulations are stable.
I am using a xy-periodicity. For this I introduced walls on both sides
of the box. My wall-atoms dont interact with any of my atoms.
For a couple weeks now, I have been trying to reproduce image charge
effects with this model, freezing a test charge (no LJ-interaction, only
a charge of +1e assigned to it) at a certain distance from the Au
surface. In the documentation it is stated that z_box should be 3 times
as big as the system when using walls with a slab geometry. I did this.
But the forces I calculate on the test charge neither match for the far
field, nor for the near field.
Do you have any suggestions on how the walls and therefore PME might
bring artifacts in? I am running out of ideas on how to fix this problem.
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