The present work discuss the Sommerfeld atom in the non-relativistic domain, using the old quantum mechanics formulation. The particle in a box, rigid rotor and harmonic oscillator energies are considered, to make the text complete. An historical introduction and a qualitative presentation of the relativistic formulation are also discussed. The text was prepared in a way to make it acessible to an undergraduated student.
Keywords:
Sommerfeld atom; Old quantum theory; Wilson-Sommerfeld quantization rules