Regarding creep deformation

LAMMPS LAMMPS Beginners
1

I have used the following creep deformation code. Sample is suppose AB2 alloy
units metal
echo both
atom_style atomic
dimension 3
boundary p p p
read_data finalalloy.lmp
timestep 0.002
pair_style eam/alloy
pair_coeff * * Pot.EAM A B
thermo 100
velocity all create 1265.0 873847 rot yes mom yes dist gaussian

Energy minimization

min_style cg
minimize 1.0e-10 1.0e-10 10000 1000

variable tmp equal lx
variable lo equal ${tmp}
variable strain equal (lx-v_lo)/v_lo

variable time equal “step* 0.0002”

variable xhigh equal xhi
variable xlow equal xlo
variable zhigh equal zhi
variable zlow equal zlo

variable p1 equal “-pxx/10000”
variable p2 equal “-pyy/10000”
variable p3 equal “-pzz/10000”

Equilibration

fix equi all nvt temp 1265 1265 0.01
run 10000
unfix equi

initializing velocities

velocity all create 1265.0 873847 rot yes mom yes dist gaussian
thermo_style custom step temp xlo xhi ylo yhi zlo zhi pe etotal press pxx vol
dump 1 all custom 10000 creep_dump@1265K*.lammpstrj id type x y z
log [email protected]

fix 3 all nve
fix def all print 500 "{time} {strain} {xlow} {xhigh} " file creep_curve_data.txt screen no

fix 7 all press/berendsen x 30000 30000 100 dilate all

run 500000

This code is running, but problem is that the temerature fluctuates.It is not at 1265 K. It continuously increases. I use nvt and nve. Instead of nve I am trying with nvt also but then creep curve is not coming.

where should I change. Any help is highly appreciated

2

There have been numerous discussions on the subject of temperature fluctuations in classical MD. Check out the archives.

That is a discussion you need to have with your adviser or somebody else that cares about your research as this is not a LAMMPS problem, but a problem of how to do the research you want to do. LAMMPS just follows the commands you give it. It is not a LAMMPS problem, if they don’t do what you expect unless your can prove without doubt (i.e. by providing proof that LAMMPS does not behave as the documentation says it would). Not getting the results you desire is no proof of that.

3

Thank you sir for comments