On the surface relaxation of transition metals

Abstract

First principles band structure calculations are presented for the layer relaxation of the close-packed surfaces of 5d transition metals. Anomalously large relaxations are found for group IVA and VIIA hcp metals. For these elements, the size of the layer relaxation exhibits an unusually slow decay with the distance from the surface. We argue that this phenomenon can be attributed to the peculiar flat and degenerate d-bands located close to the Fermi level in the L-A-H top-plane of the hcp Brillouin zone, and which are also responsible for the anomalously low [001] longitudinal optical phonon frequencies observed in these hcp metals.

Keywords:

• surface relaxation
• transition metals
• density functional theory

Acknowledgements

Support from OTKA in Hungary (Grants No. T046773, T048827, F68852 and K60576) is gratefully acknowledged. V.Z. acknowledges the János Bolyai Research Scholarship of the Hungarian Academy of Sciences. L.V. acknowledges the Swedish Research Council and the Swedish Foundation for Strategic Research for financial support.