Step 3 : make the substitutions and obtain: | Ψ Ψ ⟩ ⟩ = ∑ ∑ i 1 , i 2 , α α 1 , α α 2 Γ Γ α α 1 [ 1 ] i 1 λ λ α α 1 [ 1 ] Γ Γ α α 1 α α 2 [ 2 ] i 2 λ λ α α 2 [ 2 ] | i 1 i 2 ⟩ ⟩ | Φ Φ α α 2 [ 3.. N ] ⟩ ⟩