Elements of Classical and Quantum Physics pp 309-321 | Cite as

# Perturbation Theory

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## Abstract

Suppose we can find the bound states of some Hamiltonian \(H_{0}\) by solving exactly the time-independent Schrödinger equation \(H_{0}\psi _{n}^{(0)}=E_{n}^{(0)}\psi _{n}^{(0)}\). We calculate the discrete energy levels \(\{ E_{1}^{(0)}, E_{2}^{(0)}, E_{3}^{(0)},\ldots \}\) and find agreement with experiment. Invariably then, we wish to see what happens when we perturb the system by what we physically feel is a weak perturbation \(\hat{V}.\)

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