Chemisorption and dissociation of O2, on Ag(110)

Model studies of the chemisorption of hydrogen and oxygen on the Au (1 0 0) surface

“…This combination, which we labeled MIXRECP(II), was reasonably accurate. For Au 9 the D e increased by 2.75 kcal/mol, whereas the bond distance remained unchanged. Minot and Markowitz [41] also found that in bulk metal calculations the p valence orbital occupation is, in general, low and they could be withdrawn from a basis set without a signi®cant loss of accuracy.…”

“…In this case the O cluster binding energy increases with cluster size but seems to stabilize above Au 25 to values in the range 60± 64 kcal/mol. Only Au 25 (12,9,4) deviates somewhat, with a binding energy of 69 kcal/mol. The calculated chemisorption energy for the two smallest clusters, Au 5 and Au 9 , is only 45 kcal/mol.…”

“…From temperature-programmed desorption experiments the value of D e is estimated to be 56±64 kcal/mol. The change in occupation that occurs during the reaction in the outermost orbitals of the clusters and of oxygen is also shown (16,9) 60.41 1.20 )0.80 a1(2)b2(1) a1(2)e(2) a1(2)e(4) b2(1) A 1 Au 25 (12,9,4) 69.34 1.21 )0.77 a1(2)b2(1) a1(2)e(2) a1(2)e(4) a1(1) C 1 69.07 1.14 a1(2)b2(1) a1(2)e(2) a1(2)e(4) b2(1) A Au 29 (16,9,4) 61.9 1.23 )0.72 a1(2)e(1) a1(2)e(2) a1(2)e(4) e(1) A 1 Au 41 (16,9,16) 63.2 1.27 )0.74 a1(2)b2(1) a1(2)e(2) a1(2)e(4) b2(1) A 1 Au 50 (16,9,16,9) 63.9 1.21 0.76 a1(2) a1(2)e(2) a1 (2) orbital on the cluster to the e orbital predominantly on O. The transfer was interpreted by Siegbahn and Wahlgren [5] as being caused by a strong Pauli repulsion in symmetry A 1 owing to the interaction between a doubly occupied cluster orbital and the doubly occupied O(2p z ) orbital.…”

Adsorption, diffusion, and vibration of oxygen onAg(110)

“…Another DFT study by Olsson et al [31] claims that O 2 [001] and O 2 [11 0] have the same adsorption energy with no preference of their two orientations. In contrast, a theoretical study [32] of the energetics and dissociation of O 2 on an Ag(110) surface of an Ag 24 cluster shows that the chemisorbed O 2 lay along the [11 0] direction. And a recent DFT study [33] also finds that the adsorption of O 2 with the orientation along the [11 0] is slightly more stable than that of O 2 along the [001] (the chemisorption energy of O 2 [11 0] and O 2 [001] are found to be 0.449 eV and 0.439 eV, respectively).…”

Dipped adcluster model study for the end-on chemisorption of O2 on an Ag surface

“…The heats of molecular and dissociative chemisorptions and the 0-0 vibrational frequencies agreed well with the experimental values. In addition to other theoretical studies (12)(13)(14)(15)(16) on the side-on adsorptions of 0, onto the silver surface, which use the cluster model, the structures and electronic states of the side-on oxygen species are considerably clarified. In this study, we investigate the end-on adsorption of an O Z molecule on an Ag surface with the use of DAM.…”