Hydrogen Atom with Spin in External Fields

Abstract

Having established the properties of irreducible tensor operators, I am now in a position to use perturbation theory to study how the energy levels of the hydrogen atom are modified in external magnetic and electric fields. Before doing so, however, I will use perturbation theory to obtain the relativistic corrections to the energy levels of hydrogen in the absence of any external fields. This will lead naturally to a discussion of the fine-structure and hyperfine structure of hydrogen.