Question

Fermi liquid vs Fermi gas, when to use either one to model a metal?

Answer 1

However I'm now discovering Fermi liquids on my own and it seems that for low temperatures it is more accurate than using a Fermi gas because it does consider interactions between electrons. I fail to understand why we couldn't consider electron-electron interaction in the case of a Fermi gas and why would a liquid be more accurate. I understand the case of He33 that remains liquid even near 0K0K, but I am more interested in most metals instead. What do we lose by considering the electrons as behaving like a Fermi gas (considering both without and with e−e−- e−e− interactions) as opposed to a Fermi liquid, near 0K0K?

Answer 2

Explanation:

An ideal Fermi gas is a state of matter which is an ensemble of many non-interacting fermions. Fermions are particles that obey Fermi–Dirac statistics, like electrons, protons, and neutrons, and, in general, particles with half-integer spin. These statistics determine the energy distribution of fermions in a Fermi gas in thermal equilibrium, and is characterized by their number density, temperature, and the set of available energy states. The model is named after the Italian physicist Enrico Fermi.[1]

This physical model can be accurately applied to many systems with many fermions. Some key examples are the behaviour of charge carriers in a metal, nucleons in an atomic nucleus, neutrons in a neutron star, and electrons in a white dwarf.