Atomic and Molecular Adsorption on Re(0001)

Using periodic, self-consistent density functional theory calculations, the adsorption of several atomic (H, S, N, O and C) and molecular (CO2, N-2, NH3, HCN, CO and NO) species and molecular fragments (NH2, NH, CN, CNH2, HNO, NOH, CH3, CH2, CH and OH) on the (0001) facet of rhenium at a coverage of 0.25 ML has been studied. Preferred binding sites with their corresponding binding energy and deformation energy of the surface, as well as an estimated diffusion barrier of each species have been determined. Atomic species and molecular fragments tend to bind to threefold sites, whereas molecular species tend to bind to top sites. The binding strength, with respect to the corresponding gas phase species and in increasing order for all species studied, is: CO2 < N-2 < NH3 < CO < CH3 < HCN < NO < H < NH2 < OH < CH2 < CNH2 < CN < HNO < NH < NOH < S < N < O < CH < C. The vibrational frequencies of all species in their most energetically favorable adsorbed configuration have been calculated. Finally, the thermochemistry of adsorption and decomposition of NO, NO + H, NH3, N-2, CO2, CO and CH4 on Re(0001) has been analyzed.