Isolated Pb adstructures on Ge(1 0 0) slabs with variable thickness

Abstract

The adsorption of an isolated monomer (1 Pb adatom), dimer (2 Pb adatoms), and infinite Pb 1D chain on the Ge(100) oriented slabs of different thickness are studied using density functional theory. It was found that the energetically most favourable atomic configurations of the Pb monomers are independent of the slab thickness. On the other hand, the alternative monomer structure with Pb adatom located between two Ge-up atoms from adjacent dimer rows depends considerably on the slab thickness – the structural and electronic structures of this monomer obtained with the use of 6 and 12 layers slab are very different. The geometry and electronic structure of the parallel inter-dimer-row configuration of Pb on Ge(100) surface are reliably reproduced by relatively thin asymmetric slabs, however, structural and electronic properties of the perpendicular inter-dimer-row configuration of Pb are quite sensitive to the number of layers in the slab.