Time step
The time-step is an important variable in molecular dynamics simulations. It is usually of the order of femto (Failed to parse (SVG (MathML can be enabled via browser plugin): Invalid response ("Math extension cannot connect to Restbase.") from server "https://wikimedia.org/api/rest_v1/":): {\displaystyle 10^{-15}} ) seconds for molecular simulations.
Multiple time steps
A well known multiple time step method is the reversible reference system propagator algorithm (RESPA):