TMC(1 0 0) surface relaxation studied with low-energy-electron-diffraction intensity analysis

The atomic structures of TiC(1 0 0), NbC(1 0 0) and ZrC(1 0 0) were determined precisely by low-energy electron diffraction intensity analysis. The surface atomic structure is relaxed; topmost C atoms are displaced outward and metal atoms inward with respect to the truncated bulk atomic positions. It is consistent with the results of the force constant changes in surface phonon experiments. For TiC, the results agree qualitatively with the theoretical work [Price et al., Phys. Rev. Lett. 77 (1996) 3375] and quantitatively with the latest theoretical results based on the first-principles molecular dynamics method [Kobayashi, Jpn. J. Appl. Phys. 39 (2000) 4311–4314, Part 1, No. 7B, 30 July 2000].