Topology of Electronic Charge Density and Energetics of Planar Faults in fcc Metals

Using ab initio calculations we have studied the energetics and the evolution of the electronic charge density with shear in three fcc metals exhibiting different deformation properties, aluminum, silver, and iridium. The charge redistribution described by the change in character of specific charge density critical points (cps), is ascertained from the values of the charge density, ρ₀, and its three principal curvatures, ρ_∥∥, ρₕₕ, and ρᵥᵥ, respectively. The change in character of cps correlates with the energetics. For all three metals, ρₕₕ vanishes near the unstable stacking configuration. The symmetry or asymmetry of the charge redistribution, measured by ρₕₕ/ρᵥᵥ, may be an important factor determining stacking fault energies.