Density functional theory and slab models are employed to study NO molecule adsorption and reaction on clean and atomic oxygen precovered Au(111) surfaces. While clean Au(111) surface is catalytically inert and can only weakly adsorb NO, an atomic oxygen precovered Au(111) surface is found to be very active to NO. On the clean surface, NO prefers to bond at the onefold on-top surface site with a tilted geometry. On 0.33 ML (monolayer) oxygen precovered surface NO reacts with chemisorbed oxygen to form chemisorbed NO₂ by conquering a small energy barrier about 0.18 eV, and the desorption energy of NO ₂ is 0.64 eV. On 1.0 ML oxygen coverage surface, no barrier is found while NO reacts with precovered oxygen. The desorption energy of NO₂ is 0.03 eV. The desorption of NO₂ is the rate determining step on both surfaces and the overall reaction barriers are 0.64 and 0.03 eV, respectively. The activation energies depend on the initial coverage of oxygen, which compare favorably with experiments on Au surface with different oxygen coverages.

With density functional theory, the mechanism of water-enhanced CO oxidation on oxygen pre-covered Au (111) surface is theoretically studied. First, water is activated by the pre-covered oxygen atom and dissociates to OH_ads group. Then, OH_ads reacts with CO_ads to form chemisorbed HOCO_ads. Finally, with the aid of water, HOCO _ads dissociates to CO₂. The whole process can be described as 1/2H₂O _ads + H₂O_ads + 1/2O _ads + CO_ads → H₃O_ads + CO _{2, gas}. One CO₂ is formed with only 1/2 pre-covered oxygen atom. That is why more CO₂ is observed when water is present on oxygen pre-covered Au (111) surface. Activation energy of each elementary step is low enough to allow the reaction to proceed at low temperature

The mechanism for electron photoemission of [121]tetramantane and its functionalized compound [121]tetramantane-6-thiol adsorbed on different noble metal surfaces has been investigated by density functional theory calculations. It is found that good chemical bonding between molecules and metal surfaces is a helpful but not a necessary condition for electron photoemission. A lower work function and weaker hybridization between the molecule and the metal could lead to much more efficient electron photoemission. It is observed that, neglecting final state effect, a simple ground state picture cannot result in negative electron affinity for the systems under investigation. Calculations have shown that by exciting an electron in the lowest unoccupied molecular orbital, the highest singly occupied molecular orbital of the molecule can be shifted above the vacuum level, resulting in negative electron affinity and emission of the accumulated electrons.

Density functional theory calculations have been carried out for a benzene-1,4-dithiol (BDT)molecule adsorbed on a perfect Au (111) surface, a gold nanowire of 1 nm in diameter and alsosurface supported gold cluster (point). It is indicated that a BDT molecule prefers to adsorbon irregular surface sites. The Simulated S K-edge x-ray absorption spectra (XAS) and ultra-violet photoemission spectra (UPS) are presented. The predicted XAS spectra show that x-rayspectroscopy could be a powerful method to study the structure of molecule-metal contact.

The geometric, electronic, and magnetic properties of the FeO monolayer on a Pt(111) surface are investigated by first principles calculations. Generally, antiferromagnetic (AFM) structures are more stable than that of the ferromagnetic one. On the basis of a specific AFM structure, the long puzzling scanning tunneling microscopy (STM) experimental observations can be well explained. In this AFM model, the Fe-O layer distance at the fee region is larger than the hcp region, in contrast to previous theoretical results. The STM images at the field-emission regime are explained by local surface potential.

The adsorption of water on perfect TiO2(110) surface is studied by quantum molecular dynamics simulation adopting a periodic model formed by five water molecules on a (5 x 1) surface unit cell of a five layer slab of TiO2. The total simulation time is 3.2 ps. At about 1.3 ps, one water molecule dissociates with the help of other adsorbed waters and surface bridging oxygens. During the remaining 1.9 ps, the waters and OH groups vibrate, but no more dissociation or recombination is observed. By comparing recent experimental O1s photoemission (x-ray photoelectron spectroscopy) spectra of H2O/TiO2(110) to the computed spectrum of the adsorbate in the configurations supplied by the molecular dynamics simulation, the observed peaks can be attributed to different oxygen species. The proposed assignment of the main spectral features supports the occurrence of partial water dissociation (similar to 20%) also on a perfect TiO2 surface.

Ab initio calculations and molecular dynamics simulations were performed to investigate the adsorption mode of various oligopeptides on titanium dioxide surfaces and to characterize their conformational behavior upon adsorption. The models were progressively improved obtaining a description compatible with the experimental observations.

With the (4x1) ADM structural model proposed by Lazzeri and Selloni, the behavior of wateron reconstructed anatase TiO₂ (001) surface is studied by quantum molecular dynamics simulationsand an interpretation of the x-ray photoemission spectra, recently collected for such systems, with different water coverage, is provided. The spectrum of the low coverage phase is assigned to oxygencore ionization of only acceptor hydrogen bonded hydroxyl species, while the spectrum of the highcoverage phase is due to contributions from both donor and acceptor hydrogen bonded hydrox-yls. The experimental spectral evolution with temperature and dosing is also well interpreted bytheoretical simulations.

Chemical structure of graphene oxide is complicated by the presence of many different oxidation species. We report here a density functional theory study on binding energy of carbon 1s at different oxidation environments on a graphene oxide sheet. It is shown that the calculated results can be wellused to interpret experimental X-ray photoemission spectra of different research groups and provide united spectral assignments. New species that are important for understanding cut mechanisms of graphene oxide have been identified.

Our first principles calculations reveal that an oxidative cut of graphene is realized by forming epoxy and then carbonyl pairs. Direct formation of a carbonyl pair to tear graphene up from an edge position is not favorable in energy. This atomic picture is valuable for developing effective means of graphene manipulation. The proposed epoxy pairs may be related to some long puzzling experimental observations on graphene oxide.