Choose timestep for system

Thanks for your help. But I am still looking for a specific method to choose the time step. How do I know the time step I chose is suitable for my system?

I got some problems when I increased the time step to 2 fs of simulation. The energy jumped in my result. Should I compare the system energy result?
I tried a method is that plot the a atom trajectory. If the trajectory result behave harmonic, the timestep I selected would be reasonable. However, the trajectory result still show harmonic when the time step of system increased.

Thanks for your help. But I am still looking for a specific method to choose the time step. How do I know the time step I chose is suitable for my system?

‚Äčthese are all questions about the science and not about LAMMPS. talk to your adviser/tutor. that is the person you should discuss this with. and look up relevant information in text books and publications. they do exist.

axel.