ABSTRACT
Most physical systems exhibit interesting phenomena over a wide range of length and time scales. Typically a single method is not able to cover the full range, but different approaches are needed for different scales. In computational modeling, the main practical limitation comes from the available computing capacity: detailed models can only be studied over limited time and length scales. For example, electronic structure calculations are only practical up to tens or hundreds of atoms, and classical molecular dynamics (MD) simulations are just beginning to push the limit of a million atoms. The time scales that can be studied are at most hundreds of nanoseconds.
