Dear users,
I am trying to set up a simple atomistic Keating valence force field model with LAMMPS for zincblende material heterostructures (like e.g. InAs quantum dots in GaAs). The aim of the Keating model is to compute the change of distance between an atom and its nearest neighbours (4 for zincblende lattice) and the angles of the bonds. Do you, please, know of any procedures in LAMMPS which can do that? Specifically, the equations needed to be computed are in equation (2.47) in the following thesis: https://elib.suub.uni-bremen.de/edocs/00103899-1.pdf (the results of which I actually try to reproduce in the end).
I attach below the LAMMPS infile which I made and where I try to do that.
Can you please help me?
Thank you very much,
Petr
infile:
units metal
atom_style atomic
boundary p p p
variable no_steps equal 2000
variable ba equal 5.65325
variable da equal 6.0583
variable bx equal 200
variable by equal 200
variable bz equal 100
variable lz equal 10
variable dlz equal 20
variable duz equal 40
variable dr equal 100
region box block -\{bx\} {bx} -\{by\} {by} 0 \{bz\}
\#region box block 0 {bx} -\{by\} {by} 0 ${bz}
#create_box 3 box
create_box 4 box
region box1 block -\{bx\} {bx} -\{by\} {by} \{lz\} {dlz}
region dot cone z 0 0 \{dr\} 0 {dlz} ${duz}
#region box2 block -\{bx\} {bx} -\{by\} {by} \{lz\} {dlz}
#region dot2 cone z \{da4\} {da4} \{dr\} 0 {dlz} ${duz}
mass 1 69.723
mass 2 74.921595
mass 3 114.818
mass 4 74.921595
region del1 intersect 2 box box1
region del2 intersect 2 box dot
lattice fcc ${ba} origin 0.0 0.0 0.0 orient x 1 0 0 orient y 0 1 0
create_atoms 1 box
lattice fcc ${ba} origin 0.25 0.25 0.25 orient x 1 0 0 orient y 0 1 0
create_atoms 2 box
delete_atoms region del1
delete_atoms region del2
lattice fcc ${da} origin 0.0 0.0 0.0 orient x 1 0 0 orient y 0 1 0
create_atoms 3 region box1
create_atoms 3 region dot
lattice fcc ${da} origin 0.25 0.25 0.25 orient x 1 0 0 orient y 0 1 0
create_atoms 4 region box1
create_atoms 4 region dot
region show union 2 box1 dot
group show1 region show
#min_style hftn
min_style cg
min_modify dmax 0.0005
minimize 1e-12 1e-1 5000 5000
#fix 1 all nvt temp 0.01 0.001 0.01
fix 1 all nvt temp 20.01 10.001 0.1 #0.01
compute dsp all displace/atom
dump d all custom ${no_steps} dists.eim id c_dsp[1] c_dsp[2] c_dsp[3] c_dsp[4]
dump id all custom ${no_steps} dump.eim id ix iy iz fx fy fz
dump 2 all image ${no_steps} testim.*.jpg type type &
axes yes 1 0.05 view 89 -30 zoom 3
dump_modify 2 region box acolor 4/3/2/1 yellow/blue/green/red
dump_modify 2 region box adiam 3 2
dump_modify 2 region box adiam 4 1 #1.5
dump_modify 2 region box adiam 1 0.2 #5 #0.1
dump_modify 2 region box adiam 2 0.2 #5 #0.1
run ${no_steps} #2000