Dear lammps users,
I am having problems simulating two rigid walls in a bath of fluid particles.
I went through the respective parts of the manual and tried different combinations of keywords. I also checked corresponding threads in the mailing list, so I guess I do avoid the usual pitfalls, however apparently I must still be doing something wrong. (See my input in the end of this mail.)
My system consists of LJ particles interacting through the same potential. The walls are made of type 1 particles (having no interaction between them) while the fluid contains type 2 particles (interacting with each other as well as with wall atoms).
My idea is to use the fix rigid command for the walls and use a separate fix nvt for the fluid. I need to remove certain components of the force and all components of the torque acting on the walls.
The below input runs without any problem on my laptop however the simulation explodes (loses atoms) on my desktop machine.
I tried using fix rigid/nvt for the walls thermostatting thorough an external thermostat, or using fix rigid/nve and getting them thermostatted by the fluid. I tried to decrease the time step which didn’t help either.
I use fix recenter to avoid that the walls start drifting (can this cause any problem?).
I have the impression that the problem might arise when lammps tries to integrate the equations of motion of the rigid walls.
I am using the 16Feb2016 version of lammps.
What totally confuses me is the fact that the same simulation is fine on my laptop while it explodes on my desktop.
I guess the mistake should be something trivial. Can you spot it?
Thank you in advance.
boundary p p p
pair_style lj/cut 3.5
pair_coeff 1 1 0.0 0.0
pair_coeff 1 2 1.0 1.0
pair_coeff 2 2 1.0 1.0
mass 1 1.0
mass 2 1.0
neighbor 0.3 bin
neigh_modify delay 0 every 20 check no
neigh_modify exclude type 1 1
group wall1 id <= 512
group wall2 id 513:1024
group walls union wall1 wall2
group liquid subtract all wall1 wall2
thermo_style custom step atoms etotal ke pe temp
dump myDump all custom 1000 dump1.dat id type x y z
dump_modify myDump sort id
velocity liquid create 1 87287 loop geom
fix rig_wall1 wall1 rigid/nvt single temp 1 1 10 force * on off off torque * off off off
fix rig_wall2 wall2 rigid/nvt single temp 1 1 10 force * on off off torque * off off off
fix fix_liq liquid nvt temp 1 1 10
fix fix_rec walls recenter INIT NULL NULL