Timestep

In a molecular dynamics simulation, the timestep, δt, is the interval of time between which the potential energy is evaluated.  It is governed by the fastest degrees of motion in a system (bond vibrations), and must be set such that the system is stable and energy is conserved.  Typical values of δt for atomistic simulations are on the order of 1-2 fs, if using constraints, and up to 4-5 fs if also using virtual sites.