Lorentz oscillator model

Summary

The Lorentz oscillator model describes how a dielectric responds to light. It treats each bound electron as a damped harmonic oscillator driven by the electric field. It gives the permittivity as an explicit function of frequency, with a resonance at the natural frequency of the oscillators. It explains normal dispersion, anomalous dispersion and absorption near a resonance, and it is a basic example of a causal response function. With the restoring force removed it becomes the Drude model of metals.