As mentioned by Simic-Milosevic et al., the decay for Ag surface also decays as predicted by its 2D electron gas. However, that is only the case for the surface electrons. The bulk contribution decays at 1/r 5 rate. As mentioned in section 3.4, the expected decay rate for such a system is 1/r 2 , and the origin for such discrepancy should be further investigated.