Elastic constant..!

Dear All,
I tried to calculate the elastic constants of Cu with two versions of LAMMPS:

  1. lammps-10Sep10.tar.gz
  2. lammps-9Nov11.tar.gz

and I get two different answers for the elastic constants. I observed that the format of ‘if’ command has changed between the two versions.
With lammps-10Sep10.tar.gz, I get the following
C11 = 170GPa, C12 = 126GPa, C44 = 77.84GPa
lattice constant = 3.6093

and with lammps-9Nov11.tar.gz, I get
C11 = 167GPa, C12 = 124GPa, C44 = 76GPa
lattice constant = 3.5957

I use Cu_u3.eam potential for Copper. Let me know if I am missing something here.


Those are pretty small differences. Could just
be statistical noise due to some small round-off
change between the two versions, which are a
year+ apart.

If the "if" syntax was a problem, the code would
throw an error.