The Electronic Structures of the Clean and H Adsorbed (111) Surfaces for MC (M = Ti, Zr and Nb); DVXα MO Calculations

抄録

The electronic structures of the clean and H-adsorbed (111) surfaces for MC (M = Ti, Zr and Nb) are calculated using Discrete-Variational Xα molecular orbital (DV-Xα MO) method. The calculations for M₁₃C₁₃ clean surfaces cluster show that the characteristic density of state just below E_F is composed of mainly d-orbital of metal atom in the first layer, and the contribution of other atoms (carbon atoms in the second layer or metal atoms in the third layer) is found to be very little. Therefore, we ascribe the state just below E_F to “the surface state”, which is in good agreement with the one studied by our previous angle-resolved photoemission spectroscopy (ARPES). The calculations for the M₁₃C₁₃H₃ H-adsorbed cluster surface are more complicated; the characteristic peak of the states originated from hybridization between Hls and the surface metal d-orbitals are formed at around 6 8 eV for all cases of TiC, ZrC and NbC is shown. This result reveals that the electronic structures of these H/TiC, H/ZrC and H/NbC are essentially similar.