This work will concentrate on the mechanisms that produce neutralized atoms upon scattering of ions from metal surfaces. Three mechanisms are usually considered for ion neutralization at metal surfaces. Those are: resonance tunneling; Auger neutralization and surface plasmon-mediated ion neutralization. The third mechanism, namely surface plasmon-mediated ion neutralization, was suggested and calculated by us in an earlier work, where a unitary transformation was introduced to the second quantized Hamiltonian. The atoms are described by a state orthogonal to all conduction band states of the metal. The transformation gave rise to an additional term in the matrix elements ''the orthogonalization term''. This theory of applying a unitary transformation to the second quantized Hamiltonian is applied to the resonance and Auger neutralization mechanisms. The orthogonalization correction to the neutralization rate is found to be important at small distances from the surface when, applied to the scattering of protons from aluminum surface.