Hi all,
I have changed the script to calculated the elastic constant of FCC silver crystal.
The “potential.mod" is as the following:
pair_style eam/fs
pair_coeff * * Ag.set Ag
neighbor 0.3 bin
min_style cg
min_modify dmax ${dmax} line quadratic
thermo 1
thermo_style custom step temp pe press pxx pyy pzz pxy pxz pyz lx ly lz vol
thermo_modify norm no
The “init.mod" is as the following:
variable a equal 4.07
lattice fcc $a
region box block 0 4.0 0 6.0 0 8.0
create_box 1 box
create_atoms 1 box
change_box all triclinic
Need to set mass to something, just to satisfy LAMMPS
mass 1 1.0e-20
I got the C11=25.06Gpa, C12=77.74Gpa and C44=34.28Gpa. However, if I change the box as: region box block 0 2.0 0 3.0 0 4.0 I got a totally different result. C11=-72.76Gpa, C12=62.55Gpa and C44=23.42Gpa.
How can I fix this problem? Thanks for your help.
P.S. I have checked my outfile, the starting energies of both cells are the same. The outfile are in the attachment.
in.elastic-2-3-4.log (37.3 KB)
in.elastic-4-6-8.log (44.7 KB)