1. The need for mesoscopic methods

At the microscopic level, both quantum and atomistic methods are used. We refer the interested reader to the article on atomistic polymer simulation [AF 6 042] . Static properties are obtained by solving the time-independent Schrödinger equation, while dynamic properties are calculated by solving Newton's equation. On a macroscopic scale, the Langevin or Navier-Stokes equations are used to account for continuum mechanics. Between the two levels of representation lie mesoscopic methods, usually situated between 10 nm (10 ^–8 m) and 0.1...