lattice constant

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1

Dear Axel
it is my script:

3D simulation of master project

dimension 3
boundary p p f
units real
atom_style atomic
neighbor 2 bin
neigh_modify delay 1

#simulation box
region simbox block 0 58.3 0 38.5 0 72.2 units box
create_box 2 simbox

#create solid
lattice fcc 2.774
region wallupper block INF INF INF INF 0 9.05 units box
region walllower block INF INF INF INF 63.15 72.2 units box
region wall union 2 wallupper walllower
create_atoms 1 region wall

#create liquid
lattice fcc 5.95
region flow block INF INF INF INF 9.05 63.15 units box
create_atoms 2 region flow

#mass & energy (alpha=beta=1)
mass 1 195.084
mass 2 39.95
pair_style lj/cut 10.64
pair_coeff 1 1 12.01 2.475
pair_coeff 1 2 1.6977 2.94
pair_coeff 2 2 .2402 3.405

#groups
group flow region flow
group wall region wall
region wallsl block INF INF INF INF 0 2 units box
region wallsu block INF INF INF INF 70.2 72.2 units box
region walls union 2 wallsu wallsl
group walls region walls
group walld subtract wall walls
region pump block 0 3.405 INF INF 9.05 63.15 units box
region revel block 30 50 INF INF INF INF units box
variable countpump equal count(flow,pump)
variable force equal .10785/v_countpump

#initialize
velocity flow create 100 482748 mom yes rot yes dist gaussian
velocity walld create 100 482748 mom yes rot yes dist gaussian
velocity walls set 0 0 0
compute walldt walld temp
compute flowt1 flow temp
compute flowt2 flow temp/com
fix 1 all nve
fix 2 walld temp/rescale 20 100 100 5 .1
fix_modify 2 temp walldt
fix 3 walls setforce 0 0 0
fix 4 flow addforce v_force 0 0 region pump

Run

timestep 5
thermo 10000
thermo_style custom step time c_flowt1 c_walldt
#run 200000
dump 1 all atom 50000 re3.flow
fix 5 flow ave/spatial 1 190000 200000 y lower 3.5 vx norm sample ave running units box region revel file vel1.perofile
#fix 6 flow ave/time 1 190000 200000 v_pressure5 v_pressure6 v_pressure7 file pressure2.txt
run 5000000

and it is part of his paper:

Each
solid wall consists of four layers of molecules arranged
as a FCC lattice and its [111] surface is in contact with
the liquid.

the lattice constant 2.776 AA of platinum

I attached his paper

00b7d53c6778371802000000.pdf (1.14 MB)

2

Dear Axel
it is my script:
# 3D simulation of master project

dimension 3
boundary p p f
units real
atom_style atomic
neighbor 2 bin
neigh_modify delay 1

#simulation box
region simbox block 0 58.3 0 38.5 0 72.2 units box
create_box 2 simbox

#create solid
lattice fcc 2.774
region wallupper block INF INF INF INF 0 9.05 units box
region walllower block INF INF INF INF 63.15 72.2 units box
region wall union 2 wallupper walllower
create_atoms 1 region wall

[...]

and it is part of his paper:

i don't have time to study papers or learn what your research project
is. that is something to discuss with your adviser.

Each
solid wall consists of four layers of molecules arranged
as a FCC lattice and its [111] surface is in contact with
the liquid.

your input creates a [100] surface, not [111]. also it is generally
safer to define the simulation box as multiples of the lattice vectors
to not be subject to truncation and rounding errors. please note, that
for rotated lattices, you have to make certain that the box is large
enough to have proper periodic continuation of the lattice for all
layers.

this is all very basic stuff and not exactly specific to LAMMPS. you
should talk with the people that are training you in doing MD.
axel.