Approximation methods in quantum mechanics
We have seen how to solve some simple quantum mechanical problems exactly and, in principle, we know how to solve for any quantum mechanical problem that is the solution of Schrödinger’s equation. Some extensions of Schrödinger’s equation are important for many problems, especially those including the consequences of electron spin. Other equations also arise in quantum mechanics, beyond the simple Schrödinger equation description, such as appropriate equations to describe photons and relativistically correct approaches. We postpone discussion of any such more advanced equations.
For all such equations, however, there ...