Dear Lammps users
I am trying to build up bcc-structured Fe(100) doped with carbon atoms. I plan to place the carbon atoms in the octahedral sites. Please see scripts of the input code and log files below:
input code:
Introduction of defects into the lattice
include X.txt
include Y.txt
include Z.txt
include ID.txt
units metal
dimension 3
boundary p p s
atom_style atomic
neighbor 2.0 bin
neigh_modify delay 5
thermo 1000
----------------------------------------Define variables-----------------------------------------
variable Temp index 1 # temperature for indentation tests
timestep 0.001
variable myseed equal 482748 # the value seed for the velocity
variable atomrate equal 5000 # the rate in timesteps that the atoms are dumped
variable time_eq equal 20000 # time steps for the equilibrium process
variable time_indent equal 20000 # time steps for indentation
variable tdamp equal “v_tstep100" # damping time for thermal equilibrium
variable pdamp equal "v_tstep1000”
variable a equal 2.866 # lattice parameter for the metal
variable size equal 40 # length of the simulation box
variable height equal 20 # height of the simulation box
variable P_in equal ${size}*$a/2 # position of indentation on the X axis
variable m equal 55.85 # atomic weight gram per mole
variable r equal 50 # Tip radius in angstrom
variable k equal 0.05 # loading rate
variable s equal 10 # stiffness of the virtual indenter
print “-------------------------------Temperature=${Temp} K---------”
-------------------------------------Atom definition--------------------------------
lattice bcc a
region total block 0 {size} 0 {size} 0 {height}
region body block 0 {size} 0 {size} 3 {height}
region bottom block 0 {size} 0 ${size} 0 2
create_box 2 total
create_atoms 1 region total
variable i loop 10
label loopa
region {ID} block {X} {X}+1 {Y} {Y}+1 {Z} {Z}+1
#delete_atoms region {ID}
create_atoms 2 single {X}+0.5 {Y}+0.5 ${Z}
next X
next Y
next Z
next ID
next i
jump Fe100_C_T.txt loopa
mass 1 $m
mass 2 12
group koerper region body
group boden region bottom
#-----------------------------------Force field--------------------------------
pair_style eam/fs
pair_coeff * * FeC.eam.fs Fe C
#pair_style tersoff/zbl
#pair_coeff * * FeC.tersoff.zbl Fe C
-------------------------------------settings--------------------------------
compute myTemp all temp
compute new koerper temp
compute disp all displace/atom
compute pot all pe/atom
compute ke all ke/atom
compute s1 all stress/atom virial
variable depth1 equal $r+a*{height}+0.5-(step-${time_eq})dt$k # loading part
#------------------------------------------Equilibrium------------------------------------
#velocity all create $x 825577 dist gaussian
minimize 1.0e-6 1.0e-12 10000 100000
…
In the log file, I found the minimization failed, and the energy goes to infinity:
#velocity all create $x 825577 dist gaussian
minimize 1.0e-6 1.0e-12 10000 100000
WARNING: Resetting reneighboring criteria during minimization (…/min.cpp:173)
Memory usage per processor = 4.21951 Mbytes
Step Temp E_pair E_mol TotEng Press Volume
0 0 inf 0 inf -nan 753469
1 0 inf 0 inf -nan 753469
Loop time of 6.66577 on 45 procs for 1 steps with 65610 atoms
Minimization stats:
Stopping criterion = linesearch alpha is zero
Energy initial, next-to-last, final =
inf inf inf
Force two-norm initial, final = -nan -nan
Force max component initial, final = 0.832085 0.832085
Final line search alpha, max atom move = 0 0
Iterations, force evaluations = 1 1021
Pair time () = 4.78796 (71.8291)
Neigh time () = 0 (0)
Comm time () = 1.75883 (26.386)
Outpt time () = 0 (0)
Other time (%) = 0.118975 (1.78487)
Nlocal: 1458 ave 1514 max 1352 min
Histogram: 5 0 4 6 0 0 10 0 0 20
Nghost: 3618.69 ave 4414 max 3222 min
Histogram: 30 0 0 0 0 0 0 0 0 15
Neighs: 94537.1 ave 103422 max 85049 min
Histogram: 5 5 5 4 1 9 1 5 0 10
Total # of neighbors = 4254171
Ave neighs/atom = 64.8403
Neighbor list builds = 0
Dangerous builds = 0
velocity boden set 0.0 0.0 0.0 units box
velocity koerper create 300 ${myseed} temp new
velocity koerper create 300 482748 temp new
fix 1 boden setforce 0.0 0.0 0.0
fix 2 all temp/rescale 1000 {Temp} {Temp} 1.0 1.0
fix 2 all temp/rescale 1000 1 ${Temp} 1.0 1.0
fix 2 all temp/rescale 1000 1 1 1.0 1.0
fix 3 all npt temp 300 300 0.8 x 0.0 0.0 0.1 y 0 0 0.1 drag 1.0
dump 2 all custom 50000 initial_${Temp}K.lammpstrj id type x y z
dump 2 all custom 50000 initial_1K.lammpstrj id type x y z
run ${time_eq}
run 20000
Memory usage per processor = 3.53286 Mbytes
Step Temp E_pair E_mol TotEng Press Volume
1 256.09901 inf 0 inf -nan 753469
1000 -nan 0 0 -nan -nan -nan
2000 -nan 0 0 -nan -nan -nan
…
Could you please give me some clues about this problem? Thank you so much!
Best regards
Dong Wu
Graduate Research Assistant
Ph. D Student
Department of Material Science and Engineering
The University of Tennessee, Knoxville
log.lammps (17.2 KB)