Broken-bond rule for the surface energies of noble metals

Abstract

PACS. 71.15.Nc – Total energy and cohesive energy calculations. PACS. 71.15.-m – Methods of electronic structure calculations. PACS. 73.20.At – Surface states, band structure, electron density of states. Abstract. – Using two different full-potential ab initio techniques we introduce a simple rule based on the number of broken first-neighbour bonds to determine the surface energies of the three noble metals Cu, Ag and Au. When one bond is broken, the rearrangement of the electronic charge for these metals does not practically lead to a change of the remaining bonds. Thus the energy needed to break a bond is independent of the surface orientation, so that the surface energy is in good approximation proportional to the number of broken nearest-neighbour bonds. The surface energy represents a fundamental material property. It is given by half the energy needed to cut a given crystal into two half crystals. As such the surface energy naturally depends on the strength of the bonding and on the orientation of the surface plane. A variety of experimental techniques have been developed to measure the surface energy [1], but all measurements are performed at high temperatures where surfaces are badly defined. The