[lammps-users] putting repulsive wall

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1

Dear Steve and lammps users,

I want to use completely repulsive wall at both the ends of the simulation cell along z-direction. How will I do that? In the manual there are different fix’s like wall/lj126,wall/reflect etc. In the wall/lj126, I don’t want the 1/r^6 term. If I use wall/reflect, will it do? Or if I use wall/lj126, how will it make difference?

To do the above, first I have to use boundary command. Now which one of the following I should use.

boundary p p f or boundary p p s or boundary p p m.

Any comments and suggestions are highly appreciated. Thanking you in advance

kind regards
Bhaskar

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Dear Bhaskar,

Fix wall/lj126 is completely repulsive if you set the cut-off to the minimum in the LJ potential. If you want a hard wall, you probably want to use fix wall/reflect. You haven’t given any details about the system-type, but it is likely that the command you want is boundary p p f (no interaction with the opposite side and the box edge is at a fixed position, regardless of what the atoms are doing).

Joanne