Equating Eqs. ( ) and (3), and introducing a BHlike expansion of the electronic conditional amplitude Φ(r, t; R) = l C l (R, t)ϕ l (r; R), the relation between the nuclear amplitudes and the nuclear wavefunction becomes clear χ l (R, t) = χ(R, t)C l (R, t). In addition, since the electronic conditional amplitude satisfies the partial normalization condition |Φ(r, t; R)