Different slope in stress_strain curve

Hi my friends!
I am using LAMMPS to simulate an eam system recently. I have met a problem.
When I used boundary as “p s p” has different slope with boundary as “s s s”.
I think, these should be different on “pick” no on “slope”
I had use the commands:

units metal
atom_style atomic
boundary p s p # another runs with boundary as “s s s”

region simbox block -300 300 -300 300 -300 300 units box
create_box 2 simbox

lattice fcc 4.0500
region cube block -30 30 -30 30 -30 30 units box
create_atoms 1 region cube
set group all type/fraction 2 1 12393
mass 1 63.546
mass 2 26.9815

pair_style eam/alloy
pair_coeff * * AlCu.eam.alloy Cu Al

min_style cg
minimize 1.0e-8 1.0e-8 1000 10000

velocity all create 100 123456 mom yes rot yes

fix 0 all nvt temp 100 100 0.1
fix 1 all nve

Hi Dr.Axel…
Please guidance me … I’m confused!!!

sincerely

Nili

I don’t know much about generating stress-strain curves from MD but I can tell you that you have two time integration fixes working on all particles. That is a very bad idea.