Ab initio calculations on the anomalous thermal behaviour of fcc(1 1 0) surfaces

The interrelationship between surface structure and vibrations is explored for the case of unreconstructed (1 1 0) surfaces of face-centered-cubic (fcc) metals, which show anomalous thermal behavior in the anisotropies of surface vibrations and the change with temperature of interlayer spacings. I present the results of ab initio density functional theory calculations on Ag(1 1 0), Cu(1 1 0) and Al(1 1 0) to investigate this. These anomalous properties are shown to result from a huge enhancement in the coupling between the first and third layers of atoms. Though this may appear to be a counter-intuitive result, it can be justified using simple geometric arguments.