Hydrogen Chemisorption on Co(0001) Surface: A DFT Study

In this work the total energy calculations on the atomic geometry and chemisorption properties of Co(0001)/H surface are performed by using the density-functional theory in the approach of the projector-augmented wave (PAW) method. For a clean Co(0001) surface the atomic relaxations of the top three Co(0001) layers are obtained. The adsorptions of atomic Hydrogen have been investigated in the surface periodicities of p(1×1), p(1×2), p(2×2), and (  )R30o combined with hcp hollow and fcc hollow sites. For the cases studied in this work, the atomic hydrogen occupies fcc hollow site preferably drawn from the total energies. In these surface structures the perpendicular distances between the adsorbate and the first layer of substrate (DH-Co) range from 0.93 A to 0.99 A. The calculations on the surface vibrational modes proved the frequencies of atomic hydrogen along substrate surface displayed strong dependence on the adsorption geometries.