 Solution

ID: past-exam-of-the-chemistry-a-course-of-the-university-of-cambridge/2022/paper-1/a1/b/i/solution

The unperturbed Hamiltonian satisfies

\hat{H}^{(0)} Ψ_{i}^{(0)} = E_{i}^{(0)} Ψ_{i}^{(0)} .

The supplied eigenfunctions can be chosen as an orthonormal eigenbasis, with

⟨ Ψ_{j}^{(0)} ∣ Ψ_{i}^{(0)} ⟩ = δ_{ji}

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