Fig. 5

Scatter plots showing the discrepancies among PSPs for all the 85 elements tested. Each point in the plot corresponds to the discrepancies between pairs of PSPs (of a given element) for the two quantities tested calculated at \(E_{\mathrm {c}}^{{\mathrm{ref}}} = 200\,{\mathrm{Ry}}\). In particular we show the comparisons between the equations of state (Δ-factor in the upper panel, Δ′-factor in the lower panel) and, respectively, the pressure (δV_press), cohesive energy (δE_coh), highest phonon frequency (δω_max) and valence band structure (η_v). No strong correlations among the quantities tested are observed but we note that the Δ′-factor is more correlated to δV_press than the Δ-factor