systems such as bulk materials. Even more, if these concepts are truly valid, they should hold equally well for solids as for molecules, and should provide additional insight in the chemical properties of defects, such as dopants, interfaces and adsorption of molecules on surfaces.\
In this work, we have implemented an extension of the iterative Hirshfeld-I approach[@BultinckP:2007JCP_HirRef] to periodic systems, as a module in our HIVE-code.[@HIVE_REFERENCE] The implementation makes use of grid stored CDDs, which can easily be generated by standard solid state and quantum chemical codes.\
In Sec. \[sc:Hir\_Methods\] a short review of the parameters used in the solid state and quantum chemical codes is given. Afterwards the basic theory behind the Hirshfeld-I method is presented and extended to periodic systems. In addition, the spatial integration grid, pseudo-potentials and stored CDDs are discussed in view of the Hirshfeld-I method for periodic systems. In Sec. \[sc:Hir\_Res\_and\_Dis\] the influence of the different grids on the accuracy is discussed. We also identify a delocalization problem in the radial CDDs which originates from the plane wave approach and periodic boundary conditions (PBC) used in the solid state code, and a simple and effective solution for this issue is presented. As a last point, 