# nonperiodic boundary condition for wall

​Hi Dear all

I want to simulate a nano-channel with two Platinum walls in the Z direction (up and down) and argon gas between the walls.
I use periodic boundary condition in the x and y direction and non-periodic and fixed boundary in the z direction.
The input file is as follows:

units metal
boundary p p f
atom_style full

# Atoms definition

lattice fcc 3.920 orient x 1 0 0 orient y 0 1 0 orient z 0 0 1 &
origin 0 0 0

region box block -25 25 -25 25 -5 205 units box
create_box 2 box

region up block -20 20 -20 20 201 204 units box
create_atoms 1 region up
group up region up

region down block -20 20 -20 20 -4 -1 units box
create_atoms 1 region down
group down region down

lattice fcc 20
region ARGON block -20 20 -20 20 0 200 units box
create_atoms 2 region ARGON
group ARGON region ARGON

mass 1 195.08
mass 2 39.95

velocity down set 0.0 0.0 0.0
velocity up set 0.0 0.0 0.0
velocity ARGON create 114 4928459 dist uniform mom yes rot yes

pair_style hybrid eam lj/cut 4.5
pair_coeff * * lj/cut 0.0104 3.400
pair_coeff 1 1 eam Pt_u3.eam
pair_coeff 1 2 lj/cut 0.007611 3.2425

fix freeze1 up setforce 0.0 0.0 0.0
fix freeze2 down setforce 0.0 0.0 0.0

I have two questions:
1- If the f boundary condition is used in the z direction, then the interaction between the particle walls must be considered together?(for example EAM potential)
In fact, do particles of platinum interact with each other?

2- when f boundary condition is used this error occurs: Lost atom
What is the reason for this error?

​Hi Dear all

I want to simulate a nano-channel with two Platinum walls in the Z
direction (up and down) and argon gas between the walls.
I use periodic boundary condition in the x and y direction and
non-periodic and fixed boundary in the z direction.
The input file is as follows:

units metal
boundary p p f
atom_style full

# Atoms definition
lattice fcc 3.920 orient x 1 0 0 orient y 0 1 0 orient z 0 0
1 &
origin 0 0 0

region box block -25 25 -25 25 -5 205 units box
create_box 2 box

region up block -20 20 -20 20 201 204 units box
create_atoms 1 region up
group up region up

region down block -20 20 -20 20 -4 -1 units box
create_atoms 1 region down
group down region down

lattice fcc 20
region ARGON block -20 20 -20 20 0 200 units box
create_atoms 2 region ARGON
group ARGON region ARGON

mass 1 195.08
mass 2 39.95

velocity down set 0.0 0.0 0.0
velocity up set 0.0 0.0 0.0
velocity ARGON create 114 4928459 dist uniform mom yes rot yes

pair_style hybrid eam lj/cut 4.5
pair_coeff * * lj/cut 0.0104 3.400
pair_coeff 1 1 eam Pt_u3.eam
pair_coeff 1 2 lj/cut 0.007611 3.2425

fix freeze1 up setforce 0.0 0.0 0.0
fix freeze2 down setforce 0.0 0.0 0.0

I have two questions:
1- If the f boundary condition is used in the z direction, then the
interaction between the particle walls must be considered together?(for
example EAM potential)
In fact, do particles of platinum interact with each other?

​forces for the platinum atoms are computed, however, due to the use of fix
setforce, they are ignored. in fact, for your specific setup there is no
point in using eam, you could use pair style zero. the only force
contributions that matter for time integration are between type 1 and
either type 1 or type 2.​

2- when f boundary condition is used this error occurs: Lost atom
What is the reason for this error?