Energy Conservation


I’m new to molecular dynamics, and per my textbook, it says that molecular dynamics cannot be run using a Lennard-Jones truncated potential because energy conservation will be violated whenever atoms cross over the cutoff. “…as the potential changes discontinuously at Rc, a truncated potential is not particularly suitable for a Molecular Dynamics simulation.”

I get that shifting the potential won’t change the calculated force because the force is the derivative of the potential, but why doesn’t the current way that LAMMPS is setup lead to the violation of energy conservation?