Effects of localization of the semicore density on the physical properties of transition and noble metals

We use density functional theory to study the density of the 3sp semicore states in transition and noble metals. The first objective is to understand how semicore states influence cohesive properties which mainly depend on the valence density. We define a localization radius for the semicore density which is found to be a crucial parameter and to heavily influence the cohesive properties. The localization radius is found to be controlled by the occupation numbers of the 3d states. This offers the possibility of setting criteria for the construction of accurate large core pseudopotentials freezing the semicore states, and to a posteriori control the use of large core pseudopotentials in the modeling. We illustrate our findings with the examples of copper and titanium.