[lammps-users] Boundary conditions for pppm with external electric field

LAMMPS LAMMPS Mailing List Mirror
1

Dear Lammps developers,

I am trying to use lammps with applied external electric field, and treat the long range electrostatic interactions with ewald sum(kspace pppm). I’m using the periodic boudary conditions in all three dimensions.
I’m wondering what is the default boundary condition for this calculation in lammps outside the infinite system, i.e. is it with the conducting boundary condition (“tin foil”), or vacuum boudary condition?
Thanks.

Jihang

2

Dear Lammps developers,

I am trying to use lammps with applied external electric field, and treat the long range electrostatic interactions with ewald sum(kspace pppm). I’m using the periodic boudary conditions in all three dimensions.
I’m wondering what is the default boundary condition for this calculation in lammps outside the infinite system, i.e. is it with the conducting boundary condition (“tin foil”), or vacuum boudary condition?
Thanks.

Jihang

3

Dear Lammps developers,

I am trying to use lammps with applied external electric field, and treat
the long range electrostatic interactions with ewald sum(kspace pppm). I'm
using the periodic boudary conditions in all three dimensions.
I'm wondering what is the default boundary condition for this calculation in
lammps outside the infinite system, i.e. is it with the conducting boundary
condition ("tin foil"), or vacuum boudary condition?

tin foil.

axel.

4

Thanks for the prompt reply, Axel.
Is there anyway to use the vacuum boundary condition in lammps simulation?
Or if that require some modifications, would you please give some hint which source file should I modify?
thanks again.

Jihang

5

Thanks for the prompt reply, Axel.
Is there anyway to use the vacuum boundary condition in lammps
simulation?

why do you want to do that?

you are opening a *big* can of worms.
wouldn't it be much easier to account
for the boundary conditions in the
analysis (e.g. there are fluctuation
formula derivations for all kinds of
dielectric boundary conditions and
cutoff choices.)?

Or if that require some modifications, would you please give some hint
which source file should I modify?

if you have to ask this questions, then you
better should not think about modifying the
files. this is non-trivial code with lots and
lots of ways to mess it up and few to get it right.

cheers,
   axel.