DDCS by both methods, see Figure (\[fig5\]). We think that the observed discrepancy is related to the slightly different account of the NN interaction in the two calculations and this difference is probably emphasized with the decrease of $E_e$.

Figure (\[fig8\]) shows the fully differential angular distribution of electrons ejected in 1.5 MeV/amu O$^{8+}$ - Li(2s) collisions. $E_e$ is fixed at 1.5 eV and $q$=1.0 a.u. Figure (\[fig8\]) (a) presents the FDCS evaluated without internuclear interaction, while (b)-(d) are obtained from calculations including the NN interaction with $V_{pol}$ of (\[VP\]), (\[VPExp\]) and (\[VPExp-e\]), respectively. Considerable differences can be observed between results with and without NN interaction. The more characteristic differences are the sharpening of the FDCS in the direction of $\textbf{q}$ (positive Y axis) and the appearance of the wings in the $\pm$ X directions (perpendicular to the scattering plane) caused by the NN interaction. It is obvious from Figure (\[fig8\]) that the two small peaks in Figure (\[fig7\]) (c) at $\phi \approx$30$^o$ and 150$^o$ are due to the wings whereas calculations without NN interaction only give rise to the centroid peak at $\phi$=90$^o$. This has already been reported in [@Hubele2013] and [@WW2014]. At the same time considerable discrepancies are visible among results with different $V_{pol}$. The node of the 2s orbital is at around $r_T\approx$ 1 a.u.. This is the distance where the differences in the polarization potentials are emphasized. Moreover, the phase due to $V_{pol}$ affects the full NN phase only for $\rho \leq$ 1 a.u.. Accordingly, the strong variation of the FDCS with $V_{pol}$ supports the idea that the shape of the wings is determined by the low $\rho$ character of the NN interaction.

Weaker deviations appear between calculations with and without NN interaction for the Li(2p) ionization FDCS at q=0.3 a.u., see Figure (\[fig9\]). This FDCS is not symmetric with respect to the collision plane even for the calculation withou