fix phonon problem

Dear lammps users,

I am learning how to use fix phonon in lammps. As a first step I took examples given with this fix and I reproduced the curves from these examples. Then I generated a sample of copper with latgen program and ran phonon calculations with the same input script, but the data and map file generated by latgen. The conditions of the simulation were the same as in the example and I expected to see the same results. However, I get an output file with a lot of curves which look strange. Does anyone know what can be the problem in this case?

My input files and the output one (disp.dat) are enclosed to this mail.

Any help is appreciated.

Boris (913 Bytes) (25 KB)

cu.lmp (139 KB)

in.disp (235 Bytes)

disp.dat (5.56 KB)

The Phonon example used a primitive cell of Cu (001) surface, while yours is an FCC bulk Cu – should two different structures yield the same phonon dispersion?


Thank you, Ray. I see the point now.

22.02.2017, 21:42, “Ray Shan” <rshan@…1795…>: