スレイター–コンドン則
| Ψ m p ⟩ = A ( φ 1 ( r 1 σ 1 ) φ 2 ( r 2 σ 2 ) ⋯ φ p ( r m σ m ) φ n ( r n σ n ) ⋯ φ N ( r N σ N ) ) {\displaystyle |\Psi _{m}^{p}\rangle ={\mathcal {A}}(\phi _{1}(\mathbf {r} _{1}\sigma _{1})\phi _{2}(\mathbf {r} _{2}\sigma _{2})\cdots \phi _{p}(\mathbf {r} _{m}\sigma _{m})\phi _{n}(\mathbf {r} _{n}\sigma _{n})\cdots \phi _{N}(\mathbf {r} _{N}\sigma _{N}))}
と表わされ、2つの軌道が異なる波動関数は
| Ψ m n p q ⟩ = A ( φ 1 ( r 1 σ 1 ) φ 2 ( r 2 σ 2 ) ⋯ φ p ( r m σ m ) φ q ( r n σ n ) ⋯ φ N ( r N σ N ) ) {\displaystyle |\Psi _{mn}^{pq}\rangle ={\mathcal {A}}(\phi _{1}(\mathbf {r} _{1}\sigma _{1})\phi _{2}(\mathbf {r} _{2}\sigma _{2})\cdots \phi _{p}(\mathbf {r} _{m}\sigma _{m})\phi _{q}(\mathbf {r} _{n}\sigma _{n})\cdots \phi _{N}(\mathbf {r} _{N}\sigma _{N}))}