Simulations of nanocrystalline metals at the atomic scale. What can we do? What can we trust?

In recent years it has become possible to study the properties of nanocrystalline metals through atomic-scale simulations of systems with realistic grain sizes. A brief overview of the main results is given, such as the observation of a reverse Hall-Petch effect - a softening of the metal when the grain size is reduced. The limitations of computer simulations are discussed, with a particular focus on the factors that may influence the reliability of this kind of simulations.