We have performed density-functional calculations for III-V nitrides using the pseudopotential plane-wave method where d states of Ga and In atoms are included as valence states. Results obtained both local-density approximation (LDA) generalized gradient (GGA) exchange-correlation functional compared. Bulk properties, including lattice constants, bulk moduli derivatives, cohesive energies, band structures reported AlN, GaN, InN in zinc-blende wurtzite structures. also report some phases...

The desirable physical properties of hardness, high temperature stability, and conductivity make the early transition metal nitrides important materials for various technological applications. To learn more about nature these materials, first-principles density-functional theory calculations using full-potential linearized augmented plane wave (FLAPW) method within local-density approximation (LDA) with generalized gradient (GGA) have been performed. We investigate bulk electronic a series...

Heating of a ruthenium surface on which carbon monoxide and atomic oxygen are coadsorbed leads exclusively to desorption monoxide. In contrast, excitation with femtosecond infrared laser pulses enables also the formation dioxide. The is caused by coupling adsorbate phonon bath substrate, whereas oxidation reaction initiated hot substrate electrons, as evidenced observed subpicosecond dynamics density functional calculations. presence this laser-induced pathway allows elucidation microscopic...

To obtain insight into the structure and surface stoichiometry of copper-based catalysts in commercially important chemical reactions such as oxygen-assisted water-gas shift reaction, we perform density-functional theory calculations to investigate relative stability low-index copper oxide surfaces. By employing technique ``ab initio atomistic thermodynamics,'' identify low-energy structures that are most stable under realistic catalytic conditions found exhibit a metallic character. Three...

Hexagonal boron nitride (hBN) has recently emerged as a fascinating platform for room-temperature quantum photonics due to the discovery of robust visible light single-photon emitters. In order utilize these emitters, it is necessary have clear understanding their atomic structure and associated excitation processes that give rise this single photon emission. Here, we performed density-functional theory (DFT) constrained DFT calculations range hBN point defects in identify potential emission...

The atomic, electronic, optical, and mechanical properties of penta-like two-dimensional PdPX (X = O, S, Te) nanosheets have been systematically investigated using density functional theory calculations. All three exhibit dynamic stability on the basis an analysis phonon dispersions Born criteria, respectively. monolayers are found to be brittle structures. Our calculations demonstrate that semiconducting characteristics with indirect band gaps 0.93 (1.99), 1.34 (2.11), 0.74 (1.51) eV for X...

Abstract Phase instability poses a serious challenge to the commercialization of formamidinium lead iodide (FAPbI 3 )-based solar cells and optoelectronic devices. Here, we combine density functional theory machine learning molecular dynamics simulations, investigate mechanism driving undesired α-δ phase transition FAPbI . Prevalent iodine vacancies interstitials can significantly expedite structural kinetics by inducing robust covalency during states. Extrinsically, detrimental roles...

Basal-plane stacking faults in wurtzite AlN, GaN, and InN are studied using density-functional-pseudopotential calculations. The formation energies follow the trend exhibited for zinc-blende/wurtzite energy differences bulk materials, namely, lowest GaN highest AlN. Type-I have energy, followed by type-II faults, finally extrinsic faults. We also examine a type of intrinsic fault that has not, to best our knowledge, been previously discussed; its is slightly lower than Investigations...

The oxygen/silver system exhibits unique catalytic behavior for several large-scale oxidation (and partial oxidation) industrial processes. In spite of its importance, very little is known on the microscopic level concerning atomic geometry and chemical nature various O species that form. Using density-functional theory within generalized gradient approximation, interaction between oxygen Ag(111) surface investigated. We consider, a wide range coverages, on-surface adsorption as well...

As a first step towards gaining microscopic understanding of copper-based catalysts, e.g., for the low-temperature water-gas shift reaction and methanol oxidation reactions, we present density-functional theory calculations investigating chemisorption oxygen, stability surface oxides on $\mathrm{Cu}(111)$. We report atomic geometries, binding energies, electronic properties wide range oxygen coverages, in addition to bulk copper oxide. Through calculation Gibbs free energy, taking into...

We have performed density-functional pseudopotential calculations to investigate the electronic structure, atomic configurations, and formation energies of native point defects impurities in AlN. For defects, nitrogen vacancy has lowest energy p-type material aluminum n-type material. Under conditions is high, indicating that it will not occur high concentrations. find exhibits a different behavior zinc-blende wurtzite structures with respect higher-lying defect-induced level: materials,...

We present a density functional theory investigation of the interaction between water and cerium oxide surfaces, considering both stoichiometric reduced surfaces. study atomic structure energetics various configurations adsorption (for coverage 0.25 ML) account for effect temperature pressure environment, containing oxygen vapor, employing ab initio atomistic thermodynamics approach. Through our investigation, we obtain phase diagram water-ceria system, which enables us to discuss stability...

Results of extensive density-functional studies provide direct evidence that Cr atoms in $\mathrm{Cr}\ensuremath{\mathbin:}\mathrm{GaN}$ have a strong tendency to form embedded clusters, occupying Ga sites. Significantly, for larger than 2-Cr-atom states containing antiferromagnetic coupling with net spin the range $0.06--1.47\text{ }\text{ }{\ensuremath{\mu}}_{B}/\mathrm{Cr}$ are favored. We propose picture where various configurations coexist and statistical distribution associated...

The formation of chemisorbed O phases on Ru(0001) by exposure to ${\mathrm{O}}_{2}$ at low pressures is apparently limited coverages $\ensuremath{\Theta}\ensuremath{\le}0.5$. Using low-energy electron diffraction and density-functional theory we show that this restriction caused kinetic hindering a dense overlayer $(\ensuremath{\Theta}\phantom{\rule{0ex}{0ex}}=\phantom{\rule{0ex}{0ex}}1)$ can be formed with $(1\ifmmode\times\else\texttimes\fi{}1)$ periodicity. structural energetic properties...

We perform first-principles density-functional calculations to investigate the electronic and atomic structure formation energies of native defects selected impurities (O, Si, Mg) in InN. For p-type material, nitrogen vacancy has lowest energy. In n-type material all defect are high. discuss effect band-gap underestimate density functional theory (DFT), compare obtained using DFT (in local-density approximation, LDA) with a recently developed self-interaction relaxation-corrected (SIRC)...

Extensive density-functional theory calculations, and taking into account temperature pressure, afford a comprehensive picture of the behavior interaction oxygen Ag(111), provides valuable insight function silver as an oxidation catalyst. The obtained phase diagram reveals most stable species present in given environment thus identifies (and excludes) possibly active species. In particular, for conditions ethylene epoxidation, thin oxidelike structure is stable, suggesting that such atomic O...

To help understand the high activity of silver as an oxidation catalyst, e.g., for ethylene to epoxide and dehydrogenation methanol formaldehyde, interaction stability oxygen species at Ag(111) surface has been studied a wide range coverages. Through calculation free energy, obtained from density-functional theory taking into account temperature pressure via chemical potential, we obtain phase diagram O/Ag(111). Our results reveal that thin surface-oxide structure is most stable epoxidation...

We present density functional theory investigations of the bulk properties cerium oxides (CeO2 and Ce2O3) three low index surfaces CeO2, namely, (100), (110), (111). For surfaces, we consider various terminations including surface defects. Using approach “ab initio atomistic thermodynamics,” find that most stable structure considered is stoichiometric (111) under “oxygen-rich” conditions, while for a more reducing environment, same surface, but with subsurface oxygen vacancies, found to be...

Using density-functional theory within the generalized gradient approximation, we investigate interaction between atomic oxygen and Cu(100) Cu(110) surfaces. We consider adsorption of at various on-surface subsurface sites for coverages 1/8 to 1 monolayers (ML). find that a coverage 1/2 ML preferably binds in missing-row surface reconstruction, while on nonreconstructed is preferred 1/4 consistent with experimental results. For Cu(110), binding both added-row reconstructions coverages. up...

We report on a combined density functional theory and the experimental study of O1s binding energies X-ray Absorption Near Edge Structure (XANES) variety oxygen species Ag(111) Ag(110) surfaces. Our theoretical spectra agree with our measured results for known structures, including p(N× 1) reconstruction surface p(4 × 4) surface. Combining energy XANES yields unique spectroscopic fingerprints, allowing us to show that unreconstructed atomic is likely not present either under equilibrium...

Abstract Zeolites and amorphous silica-alumina (ASA), which both provide Brønsted acid sites (BASs), are the most extensively used solid catalysts in chemical industry. It is widely believed that BASs consist only of tetra-coordinated aluminum (Al IV ) with bridging OH groups zeolites or nearby silanols on ASA surfaces. Here we report direct observation a new type BAS based penta-coordinated species V by 27 Al-{ 1 H} dipolar-mediated correlation two-dimensional NMR experiments at high...

Structural stability and hydrogen adsorption capacity are two key quantities in evaluating the potential of metal-adatom decorated graphene for storage related devices. We have carried out extensive density functional theory calculations molecules on 12 different adatom (Ag, Au, Ca, Li, Mg, Pd, Pt, Sc, Sr, Ti, Y, Zr) surfaces where adatoms found to be stabilized double carbon vacancies, thus overcoming ``clustering problem'' that occurs pristine graphene. Ca Sr predicted bind greatest...