Structural properties of Na adsorbed on a Ge(100)2 × 1 surface: all electron, ab initio, density functional, cluster calculations

We present the first theoretical investigation of the structural properties of the NaGe(100)2 × 1 system. The binding of a single Na atom at different possible adsorption sites on the Ge(100)2 × 1 surface was studied using DMol, an all electron, ab initio local density functional cluster method. In contrast to our previous results for the NaSi(100)2 × 1 system, we find the pedestal site to have the lowest total energy. This situation differs from the Si(100)2 × 1 surface where Na atoms were found to adsorb preferentially on the cave site. Furthermore Na atoms, when covalently bonded to the Ge dangling bonds tend to symmetrize the Ge dimer.