1. Basic principles

1.1 Material modeling

An atom is a particle with non-zero volume and mass. The atom has six degrees of freedom: three directions of translation and three axes of rotation. The dynamics of an atom are therefore described by its Cartesian and angular coordinates, its momentum and its angular momentum. Three types of modeling are used, depending on the nature of the material studied.

• Point mass

Atoms whose interactions are represented by a spherically symmetrical potential field can be modeled by point masses. Dynamics then depends only on Cartesian coordinates and momentum, which are determined over time by integrating Newton's equation if the atom can be considered as a classical particle (this criterion...