Graphene Impact 2

LAMMPS input script

### Created by Eric N. Hahn ###

### ericnhahn@gmail.com ###

### Diamond impact of graphene sheets ###

### Version 0.4 ###

#------------------ Setup the simulation -------------------------

variable name Graphene_impact_0.4

log log.${name}

echo screen

dimension 3

units metal

atom_style atomic

boundary p p p

lattice custom 2.4205 a1 1 0 0 a2 0 1.73203 0 &

basis 0 0 0 &

basis 0.5 0.16666666666666666 0 &

basis 0.5 0.5 0 &

basis 0 0.6666666666666666 0

region box block -77 77 -44 44 -5 100 units lattice

create_box 1 box

region graphene block -77 77 -44 44 0 0.1 units lattice

create_atoms 1 region graphene

region graphene2 block -77 77 -44 44 8 8.1 units lattice

create_atoms 1 region graphene2

lattice diamond 3.567

region mobile sphere 0 0 150 24 units box

create_atoms 1 region mobile

group impactor region mobile

mass * 12.011

#-------------- Define Interatomic Potential -------------------

pair_style airebo/morse 3.0

pair_coeff * * CH.airebo-m C

compute 3 all pe/atom

compute 4 all stress/atom NULL virial #note, ignores thermal contribution to stress

#------------- Run the simulation for equilibration -------------

thermo 5

thermo_style custom step pe ke etotal temp lx ly lz press atoms

minimize 1.0e-10 1.0e-10 50 50

fix smaller all box/relax aniso 0.0

velocity all create 300.0 12345 dist gaussian

fix npt all npt temp 298 298 .5 x 0.0 0.0 .5 y 0.0 0.0 .5

dump eve all custom 5 dump.graphene_impact_new2020_min.* id type x y z vx vy vz c_3 fz c_4[1] c_4[2] c_4[3]

timestep 0.001

fix bp all balance 250 1 shift z 10 1

run 10

minimize 1.0e-4 1.0e-6 10 10

velocity all create 450.0 123456 dist gaussian

run 10

minimize 1.0e-4 1.0e-6 10 10

velocity all create 450.0 1234567 dist gaussian

run 10

minimize 1.0e-4 1.0e-6 10 10

unfix smaller

velocity all create 450.0 12345678 dist gaussian

run 50

group graphene1 region graphene

group graphene2 region graphene2

group graphene union graphene1 graphene2

variable ymn equal ylo+4

variable ymx equal yhi-4

variable xmn equal xlo+4

variable xmx equal xhi-4

region middle block ${xmn} ${xmx} ${ymn} ${ymx} -5 20 units box

group middle region middle

group edge subtract graphene middle

unfix npt

change_box all boundary p p s

#------------- Run the simulation for impact --------------

reset_timestep 0

velocity edge set 0 0 0 sum no units box

fix sheet edge setforce 0 0 0.0

velocity impactor set 0.0 0.0 -50.0 sum yes units box #20 A/ps = 2 km/s

undump eve

dump eve all custom 2 dump.${name}.* id type x y z vx vy vz c_3 fz c_4[1] c_4[2] c_4[3]

fix nve all nve

timestep 0.001

run 40000

print "Job's done"

"CH.airebo-m" potential can be found in the "potentials" folder of recent LAMMPS installations.