Hello! I’m trying to run a simple compressive stress simulation for a High Entropy Alloy; BCC with lattice parameter of 3.404. But when I load the dump files on Ovito & perform DXA, 779 out of 2000 are shown to have BCC structure and the remaining are ‘Other’ type. At the end of the simulation, 121 have BCC and the remainder are ‘Other’ type. The simulation has been done up to a small timeframe so far & I think for a longer time, all the structure types will be ‘Other’. Is this normal? This is the LAMMPS code:
------------------------ INITIALIZATION ----------------------------
units metal
dimension 3
boundary p p p
atom_style atomic
variable latparam equal 3.404
----------------------- ATOM DEFINITION ----------------------------
lattice bcc ${latparam}
region HEA block 0 10 0 10 0 10
create_box 5 HEA
------------------ Create different types of Atoms --------------------
create_atoms 1 region HEA
set type 1 type/fraction 2 .20 1559
set type 1 type/fraction 3 .25 7869
set type 1 type/fraction 4 .333333 3692
set type 1 type/fraction 5 .50 8016
------------------------ FORCE FIELDS ------------------------------
pair_style meam
pair_coeff * * library.meam Hf Nb Ta Ti Zr HfNbTaTiZr.meam Hf Nb Ta Ti Zr
neighbor 2.0 bin
neigh_modify delay 10 check yes
------------------------- SETTINGS ---------------------------------
compute csym all centro/atom bcc
compute potatom all pe/atom
######################################
EQUILIBRATION
reset_timestep 0
timestep 0.001
minimize 1e-4 1e- 100 1000
velocity all create 300 12345 mom yes rot no
fix 1 all npt temp 300 300 1 iso 0 0 1 drag 1
Set thermo output
thermo 500
thermo_style custom step lx ly lz press pxx pyy pzz pe temp
dump 1 all cfg 250 dump.hnttz_T1-3_velocity.comp_*.cfg mass type xs ys zs c_csym c_potatom fx fy fz
Run for at least 10 picosecond (assuming 1 fs timestep)
run 50000
unfix 1
Store final cell length for strain calculations
variable tmp equal “lx”
variable L0 equal {tmp}
print "Initial Length, L0: {L0}"
######################################
DEFORMATION
reset_timestep 0
fix 1 all npt temp 300 300 1 y 0 0 1 z 0 0 1 drag 1
variable srate equal 1.0e10
variable srate1 equal “-v_srate / 1.0e12”
fix 2 all deform 1 x erate ${srate1} units box remap x
Output strain and stress info to file
for units metal, pressure is in [bars] = 100 [kPa] = 1/10000 [GPa]
p2, p3, p4 are in GPa
variable strain equal “(lx - v_L0)/v_L0”
variable p1 equal “v_strain”
variable p2 equal “-pxx/10000”
variable p3 equal “-pyy/10000”
variable p4 equal “-pzz/10000”
fix def1 all print 100 “{p1} {p2} {p3} {p4}” file hnttz_T1-3_comp.def1.txt screen no
Use cfg for AtomEye
dump 2 all cfg 250 dump.hnttz_T1-3_strain.comp_*.cfg mass type xs ys zs c_csym c_potatom fx fy fz
Display thermo
thermo 500
thermo_style custom step v_strain temp v_p2 v_p3 v_p4 ke pe press
run 50000
SIMULATION DONE
print “All done”