In addition to the exact w λ→∞ (r), we also use w λ→∞ (r) from the shell model, which gives the best approximation to w λ→∞ (r) so far. 9 By 'exact' w λ→∞ (r), we refer to the one obtained from the specific 'strictly correlated electrons' approach for spherically symmetric systems 23 (see Ref. for further details). For comparison, we also show the weak coupling limit σx (r) = σλ=0 (r) quantity for Be, which, as previously observed, is mostly negative (except the inter-shell region). On the other hand, σλ→∞ (r) stays roughly around 1/2, with the maximum value of ∼ 0.8 at the nucleus (note from Sec. 4 that σλ=1 tends to ∼ 0.8