atoms flying for no reason

Dear lammps-users:
I encounter a strange phenomenon of atoms flying(the system collaps?). I use lammps to construct a cu system with three layers, and runs perfectly well, but when I write a restart file from the construction program, and read into another file with almost the same file for further processing, the atoms begin to fly. I can’t figure out what’s happening. I attach my files to this email, and hope you could help me. Thank you very much!

in.relaxation (1.25 KB) (1.92 KB)

In in.relaxation "read_data" is used to read a what seems to be a
restart file, so that won't work.

Atoms flying is probably due to your timestep. Is there any reason
you used different timesteps in two input scripts?