text: Because of limited computing power, specialized simulation models have been developed for various purposes depending on the time scale:
  a) Electronic scale simulations (density function theory, ab-initio molecular dynamics): sub-atomic length scale in femto-second time scale
  b) Atomic scale simulations (MD): nano to micro-meter length scale in nano-second time scale
  c) Film scale simulation (KMC): micro-meter length scale in micro to hour time scale.
  d) Reactor scale simulation (phase field model): meter length scale in year time scale.
  Multiscale modeling techniques have also been developed to deal with overlapping time scales.