Particle

class Particle : public feasst::PropertiedEntity

Particles may be a collection of sites (anisotropic) or a single site (isotropic).

The position of a site is often used as its “center” with respect to whole-particle operations such as the following:

1. distance-based particle cut-off methods

2. wrapping positions about periodic boundary conditions

3. rigid rotation of the particle

Each site has its own position which is not relative to the position of the particle. Reference sites may be stored optionally.