Theoretical studies of nickel clusters and chemisorption of hydrogen

First principles calculations of high- and low-symmetry clusters (up to Ni87) are reported. Macroscopic properties [ionization potential (IP), electron affinity (EA), and bandwidth] are not sensitive to cluster symmetry and, except for EA, are converged to bulk values by Ni87. Even for Ni87 the EA is over 2.5 eV smaller than the IP; the origin of this effect is discussed. The chemisorption of hydrogen is considered on the low-symmetry clusters, where it is found that threefold and fourfold sites are most favored with bond energies of [angle]3 eV for both types of sites. Geometries are not cluster sensitive with R (NiH) values of 1.57, 1.62, and 1.78 Å for twofold, threefold, and fourfold sites, respectively. Vibrational frequencies for these sites are 1420, 1212, and 592 cm^–1, respectively

Methanation of CO over Ni catalyst: A theoretical study

Theoretical methods (generalized valence‐bond calculations) were used to examine the bond energies and geometries of numerous species chemisorbed onto Ni clusters representing Ni surface. These results were used to obtain thermochemical information and to examine various mechanisms for the methanation of CO over Ni: CO+3H^(→)_(2(Ni)) CH_4+H_2O. It is found that chemisorbed formyl radicals (Ni–CHO) lead to a favorably appearing chain reaction that is consistent with current experimental results. In addition, we find a chemisorbed C_2 species that may be the catalytically active C_(ad) formed from dissociation of CO

High-Temperature Photochemistry and BAC-MP4 Studies of the Reaction Between Ground-State H Atoms and N2O

Article on high-temperature photochemistry and BAC-MP4 studies of the reaction between ground-state H atoms and N2O