Physical Review A
Exact perturbation theory for quantum-mechanical systems within boxes
Francisco Marcelo Fernández, Eduardo Alberto Castro
Abstract
We apply perturbation theory to the Schr\"odinger equation for a system caged in a one-dimensional box with impenetrable walls and show how to obtain the perturbation corrections to both the energy eigenvalues and eigenfunctions in a systematic exact way when the potential function within the box is a polynomial. As an illustrative example we consider a linear potential obtaining analytic expressions for the perturbation corrections in terms of the quantum number.