Loading CNT in LAMMPS

Hello all,

I am loading (tensile) CNT along its length using Tersoff Potential.

Initially, it is extending very nicely. But later on the atoms start moving just randomly and some are even lost.

Used time step: 0.5 fs

Loading rate: 0.01 in metal units (0.01 A/ps)

NVT ensemble, Temp: 300 K

Please help.