(1) Diagonalize H (find the eigenvalues of Eₙ and eigenvectors |Eₙ〉).

(2) Write |Ψ(0)〉 in terms of the energy eigenstates |Eₙ〉.

(3) Multiple each eigenstate coefficient by exp(-ι Eₙ/ħ t) to get |Ψ(t)〉.

(4) Calculate the probability P(aⱼ) = |〈aⱼ|Ψ(t)〉|²