# 6: Classical Interacting Systems

- Page ID
- 18581

- 6.4: Liquid State Physics
- The virial expansion is typically applied to low-density systems. When the density is high, where a is a typical molecular or atomic length scale, the virial expansion is impractical. There are to many terms to compute, and to make progress one must use sophisticated resummation techniques to investigate the high density regime. To elucidate the physics of liquids, it is useful to consider the properties of various correlation functions.

- 6.6: Polymers
- Linear chain polymers are repeating structures with the chemical formula (A)ₙ, where A is the formula unit and n is the degree of polymerization. In many cases (polystyrene), n≈10⁵ is not uncommon.

*In a scattering experiment, a beam of particles interacts with a sample and the beam particles scatter off the sample particles. A momentum~q and energy ~ω are transferred to the beam particle during such a collision. If \(ω = 0\), the scattering is said to be elastic. For \(ω \neq= 0\), the scattering is inelastic.*