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1

Dear LAMMPS users,

For some reasons, I am trying to move a wall in x direction. I have prepared a simple input file as follows. Harmonic bonds are defined between each wall atom and it’s three neighboring atoms.
When I use setforce command to move the wall, I don’t receive any error and the wall moves without any deflection or disorganization. But if I use SMD or velocity commands, I receive shake atoms error. it seems that some restrictions do not allow some wall atoms to move in x direction and it leads to deterioration of the wall lattice.
Could you please help me to solve the problem?

Best,
Omar

INPUT:

units real
neighbor 2.0 bin
neigh_modify delay 0 every 1 check yes
boundary p p f

#************************* styles **************************
atom_style full
bond_style harmonic
angle_style harmonic
pair_style lj/cut/coul/long 11.0

2

Are you trying to SHAKE bonds that are attached to wall atoms?

I don’t think you can do that, b/c you are presumably constraining

the wall in other ways. Hence the SHAKE constraints forces will

conflict with the other constraint forces.

Steve

3

Dear Steve,

Thanks for your answer. So, what should I do to satisfy my bond constraint?

Best,
Omar

4

I don’t know. I don’t understand you rmodel.

If you are constraining some atoms to a fixed

or moving wall, with other atoms attached to

them via harmonic bonds, then that is all you

should need to do for those atoms. Only SHAKE

molecules and bonds that are not part of the wall.

Steve