Dear all,
I want to simulate quasi-static stretch along y-direction at 0K for alpha-quartz. The structure is relaxed after cooling from room temperature. After that, I want to apply quasi-static stretching along y-direction only such that the y-side is increased by 0.00001 each step. I hope to loop this for 10 times and after each time, the structure should be relaxed. I found from online that we can put minimize command in a loop with stretching the structure incrementally. However, I am not very clear on how to fulfil this.
I attach my script in the end where I output intermediate stress&strain in a file. There are some problems in the file:
Fix print output for fix def1
1.00000000011046e-05 -0.0817324513709522 -0.36564318648842 -0.0960313824874549
1.00000000011046e-05 0.174520072522468 -0.1658028766301 0.226471384221925
1.00000000011046e-05 -0.564709020717339 -0.566876156108682 -0.4047267590484
1.00000000011046e-05 1.33305850224231 0.383342237194663 1.07880524464239
1.00000000011046e-05 -3.26166178333311 -2.10974464192211 -2.82491780546663
1.00000000011046e-05 7.11027748421183 3.47216717139645 5.94526335103269
1.00000000011046e-05 -14.7009575476715 -8.22056269333739 -12.3104819875476
1.00000000011046e-05 19.805079249192 10.1792292234112 16.9360698950953
1.00000000011046e-05 -38.8945644375914 -21.8577323625349 -32.7842146897005
1.00000000011046e-05 35.6893543000372 18.4028751919197 31.1743306861121
1st column is strain which should by 0.00001 each time; 2-4th columns are pressures along x, y, z direction which seems not be relaxed.
I have checked that, until unfix 2, the structure is indeed relaxed. The question is how to simulate quasi-static stretching then.
Many thanks
Bingyu Cui
#Initialization############################################################
units metal
dimension 3
boundary p p p
atom_style charge
Atom definition##########################################################
lattice custom 5.4047 &
a1 0.9092 0.0000 0.0000 &
a2 -0.4546 0.7873 0.0000 &
a3 0.0000 0.0000 1.0000 &
basis 0.4697 0.0000 0.0000 &
basis 0.0000 0.4697 0.6667 &
basis 0.5303 0.5303 0.3333 &
basis 0.4133 0.2672 0.1188 &
basis 0.2672 0.4133 0.5479 &
basis 0.7328 0.1461 0.7855 &
basis 0.5867 0.8539 0.2145 &
basis 0.8539 0.5867 0.4521 &
basis 0.1461 0.7328 0.8812
region simbox block 0.0 7.0 0.0 7.0 0.0 7.0 units lattice
create_box 2 simbox
create_atoms 1 box basis 1 1 basis 2 1 basis 3 1 basis 4 2 basis 5 2 basis 6 2 basis 7 2 basis 8 2 basis 9 2
mass 1 28.0855
mass 2 15.9994
group siliconatoms type 1
group oxygenatoms type 2
set group siliconatoms charge 2.4
set group oxygenatoms charge -1.2
Atoms interactions settings##################################
Si type 1, O type 2
pair_style table linear 64644 pppm
pair_coeff 1 1 potential.Ewald SiSi
pair_coeff 1 2 potential.Ewald SiO
pair_coeff 2 2 potential.Ewald OO
kspace_style pppm 1.0e-6
kspace_modify gewald 0.31465093412
kspace_modify kmax/ewald 23.19 13.39 17.01
neighbor 2.0 bin
neigh_modify every 1 delay 0 check yes
pair_write 1 2 10001 r 0.51 10.17 tableEW.txt Si_O 2.4 -1.2
pair_write 2 2 10001 r 0.51 10.17 tableEW.txt O_O -1.2 -1.2
pair_write 1 1 10001 r 0.51 10.17 tableEW.txt Si_Si 2.4 2.4
Equilibrate
velocity all create 298.0 635845 dist gaussian
fix 0 all npt temp 298.0 0.1 0.1 iso 1.01325 0.0 1.0
thermo_style custom step temp pe etotal press vol density lx ly lz pxx pyy pzz pxy pxz pyz fmax
thermo 10000
dump 1 all atom 10000 dump.qua
run 80000
fix 2 all box/relax x 0.0 y 0.0 z 0.0 vmax 0.005
min_style cg
minimize 1e-25 1e-25 5000 10000
unfix 0
unfix 2
reset_timestep 0
variable tmp equal “ly”
variable L0 equal ${tmp}
print “Initial Length, L0: ${L0}”
fix 3 all npt temp 0.1 0.1 0.1 x 0.0 0.0 1.0 z 0.0 0.0 1.0
min_style cg
minimize 1e-25 1e-25 5000 10000
change_box all y scale 1.00001 remap
variable strain equal “(ly-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 1 “{p1} {p2} {p3} {p4}” file Al_SC_100.def1.txt screen no
thermo 1
thermo_style custom step v_strain temp v_p2 v_p3 v_p4 ke pe press
run 10