How to confine argon particles in a T-region with periodic boundary conditions

LAMMPS LAMMPS Mailing List Mirror
1

Dear Lammps Users,

I am trying to simulate the evaporation of liquid argon between copper walls. My question is that how I can confine the argon particles in a T-region. I have attached the figure of the computational domain to this email.

I actually used “dynamic group” for vapor argon group and “fix wall/reflect” for the boundaries of the vapor region but I received an error that the fix does not allow use of dynamic group.

Any other idea that can also satisfy the periodic boundary condition?

Many thanks in advance!

Santiago

ar-cu.jpg

2

Dear Axel and Users,
I am getting an error when I run my gcmc simulation. in case of molecular template command like offset. I give a brief view of my file set up in input script below

units real
dimension 3
boundary p p p
atom_style full
atom_modify map array
pair_style lj/cut 12.5

variable a loop 8
variable p index 0.8 0.85 0.9 0.95 1.0 1.05 1.1 1.15

molecule gas gas1.molecule offset 4 0 0 0 0 # molecule templates

read_data cua1.data

log log Cu_D_$a

molecule gas gas2.molecule # molecule templates

molecule gas gas2.molecule 4 0 0 0 0 # molecule templates

Define interatomic potential

pair_style lj/cut 12.5
pair_coeff 1 5 0.0664 3.1275 #Ni
pair_coeff 3 5 0.16771 3.3815 #O
pair_coeff 2 5 0.16718 3.6015 #C
pair_coeff 4 5 0.06684 3.288 #H
pair_coeff 5 * 0.053649 2.8 #gas
pair_coeff 6 * 0.156973 3.05

Define groups fixes computes (see LAMMPS manual)

group gas type 5 6
group sol type 1 2 3 4

neigh_modify exclude molecule sol

neigh_modify exclude molecule gas

fix 1 all rig nvt temp 298 2 0

fix 2 gas gcmc 1 1000 1000 0 3366593 298.0 -0.5 0.1 mol gas pressure $p fugacity_coeff 1

fix 1 gas gcmc 100 10 10 0 34565 300.0 -0.5 0.1 maxangle 10.0 mol gas

Simulation data output and dump options

compute_modify thermo_temp dynamic yes
log Cu_DO_$a

thermo 10
thermo_style custom step atoms vol cella cellb cellc cellalpha cellbeta cellgamma
dump 2 all custom 1 dump_all id type x y z

dump m1 all image 1 all*.jpg type type view 0.0 45

dump aa gas image 5 gas.*.jpg type type

3

Not clear on why you need a dynamic group. But I don’t
think there is a conceptual problem with allowing fix wall/reflect
to use a dynamic group. Axel can comment. If it’s OK,
he can make the simple code change to enable it I GHub,
so that is is soon added to LAMMPS.

Steve

4

walls for standard point particle interactions, which includes fix
wall/reflect, are fine with dynamic groups, since there are no checks
and other requirements. i've just added the suitable changes to a
pending pull request. this change should be included in the next
LAMMPS patch.

axel.