Pertubation Theory lets you approximate the eigenvalues and eigenvectors of a particularly difficult Hamiltonian. However, we must be able to express the Hamiltonian we would like to solve (H) as the sum of another Hamiltonian with a known solution (H0), and a small pertubation (V').
Example: 1-D Infinite Square Well with Constant Pertubation
The Hamiltonian of this system is just the Infinite Square Well Hamiltonian, with an added constant potential.
To learn more HTML/CSS, check out these tutorials!