[lammps-users] lattice parameter

Dear lammps users
when i tried to find the equilibrium lattice parameter of Al at 300K by writing box dimensions i got the following output why is my lattice parameter not decreasing to 4.05A (it is its original lattice parameter at this temperature)

Input

bulk Al lattice

units metal
atom_style atomic

lattice bcc 5
region box block 0 15 0 15 0 15
boundary p p p
create_box 1 box
create_atoms 1 box

pair_style eam/fs
pair_coeff * * Al_mm.eam.fs Al

thermo_style custom step lx ly lz
fix 1 all nvt 300 300 100
timestep 0.0005
thermo 1000

run 10000

output:

Step Lx Ly Lz
0 75 75 75
1000 75 75 75
2000 75 75 75
3000 75 75 75
4000 75 75 75
5000 75 75 75
6000 75 75 75
7000 75 75 75
8000 75 75 75
9000 75 75 75
10000 75 75 75

Hi babu,

You simulation is performed with a NVT ensemble, which means
that the volume of the box will not change at all.
You can try to use the NPT ensemble instead.

L. Wan

2009/7/16 udayagiri sai babu <[email protected]…24…>