  In this letter the conceptual and computational implications of the Hartree
product type nuclear wavefunction introduced recently within the context of the
ab initio non-Born-Oppenheimer Nuclear-electronic orbital (NEO) methodology are
considered. It is demonstrated that this wavefunction may imply a
pseudo-adiabatic separation of the nuclei and electrons and each nucleus is
conceived as a quantum oscillator while a non-Coulombic effective Hamiltonian
is deduced for electrons. Using the variational principle this Hamiltonian is
employed to derive a modified set of single-component Hartree-Fock equations
which are equivalent to the multi-component version derived previously within
the context of the NEO and, easy to be implemented computationally.
