A work by Simic-Milosevic et al. illustrates the intricate balance between attractive and repulsive interactions. They showed that at the temperature of 8 K, Li adatoms on Ag(001) surface form diatomic structures with 7-9 Å Li-Li separations. Although no oscillatory feature is present on the reported STM images, perhaps due to high bias voltage of 0.3 V, FOs may still be used to explain this result. From previous studies the surface kF for Ag(111) is equal to 0.083 Å -1 94 and k bulk F = 1.2 Å -1 23 . However, in the case of Ag(001), the surface state is empty, as is the case for Ag(100), due to the same geometry, and consequently, the Fermi surface of the two. Therefore, the FOs may only originate from the bulk electron states. The periodicity found for the latter is equal to 4.55 Å. The absence of Li-Li pairs of such distance may be explained by repulsion between the two atoms, and therefore, the Li-Li pairs should form at the second potential energy minima (9.1 Å), which coincides with the above-mentioned separation of 7-9 A.