A full nonlocal model potential is employed to calculate the screened electron charge density n(EC)(q) and to construct the interatomic pair potential, which is then used in the modified hypernetted-chain integral equation to determine the ion-ion static structure factor S-ii(q). These two basic quantities are subsequently used as input data for the calculation of the electron-ion correlation. For the simple liquid metals Na, Mg, and Al, our calculated electron-ion structure factors S-ei(q) agree very well with the positions of extrema of the experimental or computer-simulated S-ei(q). Quantitative analysis of the two main contributions, n(EC)(q) and S-ii(q), shows that S-ei(q) obtained in a full nonlocal pseudopotential theory is in general different from that in the local pseudopotential theory. Such disparities in the two theoretical frameworks arise from the nonlocality of electron-ion pseudopotential, which, for a quantitative study, should be incorporated in the theory especially when one is treating the correlations of electrons and ions on an equal footing. At the level of achievement attained in this work, there is now a greater hope of understanding the electron-ion correlations if experimental errors for S-ei(q) are considerably reduced.
