Adiabatic potential-energy surfaces for oxygen on Al(111)

Nanoscale oxide growth on Al single crystals at low temperatures: Variable charge molecular dynamics simulations

“…Indeed, during the dissociation process, oxygen atoms belonging to the same molecule move away from each other when approaching the surface. In particular, when oxygen pairs ͑or Al-O clusters͒ are already present, the O atoms try to deposit directly on the cluster edges as suggested by Kiejna et al 26 Note also that oxygen molecules arriving on oxidized region of the Al surface do not have a vertical orientation but try rather to be horizontal when approaching the oxygen cluster ͑or pair͒ already adsorbed. This is in contrast to oxygen molecules that arrive vertically on a "clean" region of the Al surface.…”

“…10 are a 2D representation and some distortion in the perpendicular direction is not excluded. Kiejna et al 26 suggested that the most stable O-͑1 ϫ 1͒ subsurface structure is found in tetrahedral sites below the topmost Al atomic plane. This is in fact an idealized picture since more detailed investigation of these sections of atoms showed that some oxygen atoms are indeed below the topmost Al atomic plane and others are located in the plane.…”

“…10͑a͒ have neighbors in the perpendicular direction and these neighbors are not always shown since they are out of the selected section of atoms that is very thin ͑ϳ3-Å thick͒. Kiejna et al 26 have performed DFT calculations to study the stability of the hcp and fcc hollow sites on the Al ͑111͒ surface for oxygen deposition. In our work, we have seen that oxygen atoms are adsorbed on both sites ͑fcc and hcp͒ and that due to the lack of robust statistics we cannot conclude which sites is more favorable.…”

“…These works focused on the first stages of the O 2 molecule reaction with the Al surfaces, [24][25][26][27] the dissociation process, 28,29 and the stability of adsorption sites. 30 However, the dynamic behavior of the growth process cannot be studied by such approaches which do not include thermal vibrations and are confined to very small system sizes.…”

Generation and orientation of organoxenon molecule H–Xe–CCH in the gas phase

“…7 A straightforward explanation for this finding would be the existence of energy barriers towards dissociation that cannot be overcome by low energy, thermal molecules. Several first-principles theoretical studies employing density-functional theory (DFT) were carried out in order to identify these barriers on the potential-energy surface (PES) 11,12,13 , but were unable to find any sizeable barriers. Consequently, although no explicit calculation of the sticking curve based on the high-dimensional PES was done, it was concluded that the adiabatic PES studied by these DFT calculations cannot explain the experimental findings.…”