Numerical irreversibility in time-reversible molecular dynamics simulation

It is demonstrated that in the molecular dynamics simulation for the N-body system, even a negligibly small deliberate noise can cause irreversibility, or the loss of reversibility. This demonstration is unique and clear in that it is based on the “bit-reversible algorithm” which is, unlike the standard molecular dynamics simulation being unable to avoid round-off errors, completely time-reversible and is free from any round-off error. It is also confirmed that the irreversibility is closely related to the extent of the instability of the system, in that the more unstable the system is, the more quickly the irreversibility appears and the more rapidly the irreversibility prevails.