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lammps/examples/comb/in.comb.Cu2O.elastic
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in.comb.Cu2O.elastic
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# Cu2O crystal, qeq on, minimizes, then calculates elastic constants
units metal
atom_style charge
dimension 3
boundary p p p
read_data data.Cu2O
mass 1 63.54
group type1 type 1
compute charge1 type1 property/atom q
compute q1 type1 reduce ave c_charge1
mass 2 16.00
group type2 type 2
compute charge2 type2 property/atom q
compute q2 type2 reduce ave c_charge2
velocity all create 1.0 277387
pair_style comb
pair_coeff * * ffield.comb Cu O
neighbor 0.5 bin
neigh_modify every 20 delay 0 check no
timestep 0.00020
thermo_style custom step temp etotal pe evdwl ecoul c_q1 c_q2 lx ly lz vol
thermo_modify norm yes
thermo 1
fix 1 all nve
fix 2 all qeq/comb 1 0.0001
#dump 1 all cfg 1 *.cfg id type xs ys zs q f_2 vx vy vz fx fy fz
#dump_modify 1 element Cu O
run 2
unfix 1
fix 1 all box/relax aniso 0.0 vmax 0.001
minimize 1.0e-14 1.0e-20 1000 10000
min_modify dmax 0.2 line quadratic
unfix 1
fix 1 all nve
run 1
unfix 1
unfix 2
#undump 1
### copy lines after this to any input script for elastic calculations ###
## Elastic constants calculations: strain box, measure box stress
## strain x, measure s_x, s_y, s_z, s_yz:
## calculates C11, C12, C13 and C14
fix 2 all deform 1 x scale 1.0001 remap x
compute perfx all stress/atom NULL pair
compute fx all reduce sum &
c_perfx[1] c_perfx[2] c_perfx[3] &
c_perfx[4] c_perfx[5] c_perfx[6]
thermo_style custom step lx ly lz xy xz yz &
c_fx[1] c_fx[2] c_fx[3] c_fx[4] c_fx[5] c_fx[6]
run 10
## strain z, measure s_z: calculates C33
fix 2 all deform 1 z scale 1.0001 remap x
compute perfz all stress/atom NULL pair
compute fz all reduce sum &
c_perfz[1] c_perfz[2] c_perfz[3] &
c_perfz[4] c_perfz[5] c_perfz[6]
thermo_style custom step lx ly lz xy xz yz &
c_fz[1] c_fz[2] c_fz[3] c_fz[4] c_fz[5] c_fz[6]
run 10
## strain yz, measure s_yz: calculates C44
fix 2 all deform 1 yz erate 0.0001 remap x
compute perfyz all stress/atom NULL pair
compute fyz all reduce sum &
c_perfyz[1] c_perfyz[2] c_perfyz[3] &
c_perfyz[4] c_perfyz[5] c_perfyz[6]
thermo_style custom step lx ly lz xy xz yz &
c_fyz[1] c_fyz[2] c_fyz[3] c_fyz[4] c_fyz[5] c_fyz[6]
run 10
## strain xy, measure s_xy: calculates C66
fix 2 all deform 1 xy erate 0.0001 remap x
compute perfxy all stress/atom NULL pair
compute fxy all reduce sum &
c_perfxy[1] c_perfxy[2] c_perfxy[3] &
c_perfxy[4] c_perfxy[5] c_perfxy[6]
thermo_style custom step lx ly lz xy xz yz &
c_fxy[1] c_fxy[2] c_fxy[3] c_fxy[4] c_fxy[5] c_fxy[6]
run 10
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