 Drude model

The Drude model describes classical charge carriers accelerated by an applied electric field and randomized by collisions of constant mean waiting time $\tau$. Its mean drift obeys $\dot{v}+v/\tau =eE/m$, and harmonic conductivity is $n{e}^2\tau /[m(1-i\omega \tau )]$ in the negative-frequency exponential convention.

The Drude model is a classical model that describes the electrical and thermal properties of metals. Developed by physicist Paul Drude in 1900, this model treats conduction electrons in a metal as a gas of free, non-interacting particles. It provides a simple framework for understanding how electrical conductivity arises in metals and is foundational in solid-state physics.