I’m trying to use the command fix wall/piston only on a group of atoms, but it does not seem to do anything to the data I’m using. This is the code I’m wrote
1. Initialisation
units metal
dimension 3
boundary s s s
atom_style atomic
timestep 0.001
neighbor 2.0 nsq
2. system definition
read_data datrec3k.lammps
group forced type 2
group boundary type 1
group relaxed type 3
3. simulation settings
pair_style rebo
pair_coeff * * CH.rebo C C C
fix freeze boundary setforce 0.0 0.0 0.0
fix pist forced wall/piston zlo pos 5 vel 0.0 units box
thermo 10
thermo_style custom step etotal fmax fnorm
thermo_modify norm yes
dump 1 all xyz 100000 dump-rec3kpiston.txt
dump_modify 1 element C C C
4. run the simulation
min_style fire
minimize 0.0 3.12e-4 1000000 10000000
I have try using it both with and without velocity, and using the ramp option. Non of these things seems to work.