Add an External Force to Break the Structure of my System

Dear all,
I want to investigate what happens when the structure of my MD simulation system has been broken. In my simulation system, I have fixed the positions of atoms at left side and added an extremely large force on the atoms at right side of my system, my simulation system and perl script were shown in these two figures below:
User-added image


User-added image

During the simulation time, my system has deformed a lot, the figure below shows one frame of simulation:
User-added image

However, the chemical bonds of my systems were not broken yet although I have already add an extremely large force on my simulation system. How to break the structure of my system? Are the chemical bonds in my system unbreakable? Thank.
Best regards,
Yours
CHENG Xu