I'm an undergraduate reading up on some quantum physics so that I can help out more in the lab that I'm working in this summer. In the book I'm reading (Shankar's "Principles of Quantum Mechanics") I just came across the term interaction Hamiltonian in describing how orbiting electrons interact with a magnetic field.
I have an idea of what it might mean, but I can't find a good explanation anywhere. What is an "interaction Hamiltonian", and how does it differ from a standard Hamiltonian?
Best Answer
Any Hamiltonian contains kinetic and potential parts. Interaction means the potential part of the Hamiltonian.
Sometimes a part of interaction can be treated exactly together with the kinetic part. They form an approximative or "non perturbed" Hamiltonian. The rest of interaction is then treated perturbatively and is called "a perturbation". Interaction of the atomic electron with an external magnetic field is such part of the total Hamiltonian.