Help for tension simulation

Hi, everyone,
I am doing a tension simulation for Si and want to get the stress-strain curve. it can run but the stress goes very high like 20Gpa. I don’t know why. Can you give me some suggestions? Thanks a lot.

boundary p p p
units metal
atom_style atomic
neighbor 2.0 bin
neigh_modify delay 1 check yes

create geometry

read_data data.si_no_hole

LJ potentials

pair_style tersoff
pair_coeff * * Si.tersoff Si

compute press all pressure thermo_temp


reset_timestep 0
timestep 0.001
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 1000
thermo_style custom step lx ly lz press pxx pyy pzz temp

Run for at least 10 picosecond (assuming 1 fs timestep)

run 30000
unfix 1

Store final cell length for strain calculations

variable tmp equal “lx”
variable L0 equal {tmp} print "Initial Length, L0: {L0}"

Why do you say that the stress is HIGH…?? To what value you want to compare this value of 20GPa…? I mean, when we say HIGH, it means with respect to something/some value, what is it.??

In a nut shell, what value do u expect??


I mean the Yield stress is very high. My result is 20 Gpa while other’s is 9 in their puplished paper.

2013/4/2 Sagar Chandra <tikku.chandragarg@…24…>

In the deformation section your script has a fix npt and a fix deform acting on the system at the same time. Weird…


I think the high yield stress has something to do with the enormous strain rate of 10^11. Try reducing it.