From the initial state of an electron and a proton in a box. I would like to find a reasonable hamiltonian, or way to describe the interaction that leads to the formation of a Hydrogen atom.
Here is the initial would like to go from.
For |e> and |p> the electron and proton in an eigenstate of a particle in a 1D box, at some $n_e$ and $n_p$ energy levels. (so $E_n = \frac{n^2\pi^2\hbar^2}{2mL^2}$, with $m$ the mass of the particle in consideration, and $L$ the length of the box). Then I define my initial state $$|\psi(0)> = |e>\otimes |p>$$ An electron and proton can bind to form a hydrogen atom (potentially excited at some energy level). So I would like the initial state to evolve to something like the following. $$|\psi(T)>=|a>\otimes|\gamma>$$ Where $|a>$ is a hydrogen atom state (delocalized in the box?), and $|\gamma>$ is a photon emitted by the process.
I understand the process could emit more than one photon or involve other particles. But I would like to consider, if possible a simplified process, as I would later like to add more protons and electrons to my box.
What is a good hamiltonian to describe my evolution to the atom state?