General trend of strain effect on the adsorption and reactions over metal surfaces

Theory-Guided Machine Learning Finds Geometric Structure-Property Relationships for Chemisorption on Subsurface Alloys

We present first-principles investigations of the properties of piezoelectric oxides and metal surfaces. Our oxide work elucidates important fundamental relationships between local atomic structure and macroscopic properties of piezoelectrics. We develop a new semiempirical model to study large supercells of disordered complex oxides. We also present our computational materials design studies of proposed new perovskites. In particular we demonstrate for the first time the off-centering behavior of silver ions, which may lead to environmentally friendly silver-based piezoelectrics. Examining the chemical properties of metal surfaces, we present our studies in vacancy formation, the effects of strain on the adsorptive properties of metal surfaces and self assembled monolayers. We find that vacancy formation leads to electronic spillout and a strengthening of the bonds between the neighboring atoms accompanied by an inward relaxation. Our calculations show that the effect of strain on the chemisorption is sensitive to changes in coverage, metal identity and surface plane. In our studies on self assembled monolayers, we examine the complex adsorption process and the potential energy surfaces for adsorption of thiols on noble metal surfaces. We also show that formation of ordered thiol structures is favorable on Al(111) surface, indicating a possible use of self-assembled monolayers as a anticorrosion protective coating.

We show, by first-principles calculations, that the effect of external strain on surface diffusion is inherently correlated with the intrinsic surface stress induced by the adatom along its diffusion pathways. We demonstrate a simple generic method for a priori predicting quantitatively how an external strain will change surface diffusion on any given surface, based on calculations of surface-stress tensors of the unstrained surface.

In this paper we report calculations of the effect of uniaxial strain on the Fermi surface of the noble metals for tension along 〈001〉 and 〈111〉 directions. The calculations are performed using frozen potentials within the linear-muffin-tin-orbital method in the atomic-sphere approximation. The strain derivatives [d(lnA)/d(ln${\mathit{A}}_{\mathit{s}}$)] are calculated in the local-density approximation for various exchange-correlation potentials. The results are compared with the available experimental data as well as with earlier calculations.

Coadsorption of CO and O over strained metal surfaces

Effect of strain on the reactivity of graphene films

ChemInform is a weekly Abstracting Service, delivering concise information at a glance that was extracted from about 200 leading journals. To access a ChemInform Abstract of an article which was published elsewhere, please select a “Full Text” option. The original article is trackable via the “References” option.

Metal supported oxide nanostructures are discussed within the framework of the "inverse model catalyst" concept. We show that oxide nanostructures on metal surfaces may be regarded as artificial oxide materials, which display novel properties as compared to bulk oxide compounds and are stabilised by interfacial interactions and two-dimensional confinement effects. This is illustrated for prototypical examples of vanadium oxide overlayers on Rh(111) and Pd(111) surfaces. Structure and morphological changes of the oxide phase on V-oxide/Rh and V-oxide/Pd inverse catalyst surfaces are discussed, and the mass transport problem in catalyst systems during oxidation-reduction cycles is addressed. We demonstrate that the diffusion of oxide cluster over the metal surface provides a effective means of mass transport. The role of metal-oxide interface in determining the oxide nanolayer structure on particular substrate surfaces is investigated, and interfacial chemistry and interfacial strain effects are identified as important parameters.

Self-consistent density functional calculations for the adsorption of O and CO, and the dissociation of CO on strained and unstrained Ru(0001) surfaces are used to show how strained metal surfaces have chemical properties that are significantly different from those of unstrained surfaces. Surface reactivity increases with lattice expansion, following a concurrent up-shift of the metal $d$ states. Consequences for the catalytic activity of thin metal overlayers are discussed.

Metal surfaces have long been known to reconstruct, significantly influencing their structural and catalytic properties. Many key mechanistic aspects of these subtle transformations remain poorly understood due to limitations of previous simulation approaches. Using active learning of Bayesian machine-learned force fields trained from ab initio calculations, we enable large-scale molecular dynamics simulations to describe the thermodynamics and time evolution of the low-index mesoscopic surface reconstructions of Au (e.g., the Au(111)-‘Herringbone,’ Au(110)-(1 × 2)-‘Missing-Row,’ and Au(100)-‘Quasi-Hexagonal’ reconstructions). This capability yields direct atomistic understanding of the dynamic emergence of these surface states from their initial facets, providing previously inaccessible information such as nucleation kinetics and a complete mechanistic interpretation of reconstruction under the effects of strain and local deviations from the original stoichiometry. We successfully reproduce previous experimental observations of reconstructions on pristine surfaces and provide quantitative predictions of the emergence of spinodal decomposition and localized reconstruction in response to strain at non-ideal stoichiometries. A unified mechanistic explanation is presented of the kinetic and thermodynamic factors driving surface reconstruction. Furthermore, we study surface reconstructions on Au nanoparticles, where characteristic (111) and (100) reconstructions spontaneously appear on a variety of high-symmetry particle morphologies.

The dissociative adsorption of molecular oxygen on metal surfaces has long been controversial, mostly due to the spin-triplet nature of its ground state, to possible non-adiabatic effects, such as an abrupt charge transfer from the metal to the molecule, or even to the role played by the surface electronic state. Here, we have studied the dissociative adsorption of O2 on CuML/Ru(0001) at normal and off-normal incidence, from thermal to super-thermal energies, using quasi-classical dynamics, in the framework of the generalized Langevin oscillator model, and density functional theory based on a multidimensional potential energy surface. Our simulations reveal a rather intriguing behavior of dissociative adsorption probabilities, which exhibit normal energy scaling at incidence energies below the reaction barriers and total energy scaling above, irrespective of the reaction channel, either direct dissociation, trapping dissociation, or molecular adsorption. We directly compare our results with existing scanning tunneling spectroscopy and microscopy measurements. From this comparison, we infer that the observed experimental behavior at thermal energies may be due to ligand and strain effects, as already found for super-thermal incidence energies.

Effects of fluoride concentration and elastic tensile strain on the corrosion resistance of commercially pure titanium

The effect of external strain on surface properties of simple metals is\nconsidered within the modified stabilized jellium model. The equations for the\nstabilization energy of the deformed Wigner-Seitz cells are derived as a\nfunction of the bulk electron density and the given deformation. The results\nfor surface stress and work function of aluminium calculated within the\nself-consistent Kohn-Sham method are also given. The problem of anisotropy of\nthe work function of finite system is discussed. A clear explanation of\nindependent experiments on stress-induced contact potential difference at metal\nsurfaces is presented.\n

The effect of uniaxial strain on surface properties of simple metals is considered within the stabilized jellium model. The modified equations for the stabilization energy of the deformed Wigner-Seitz cells are derived as a function of the bulk electron density and the given deformation. The model requires as input the density parameter ${r}_{s},$ the Poisson ratio, and Young's modulus of the metal. The results for surface energy, surface stress, and work function of simple metals calculated within the self-consistent Kohn-Sham method are also presented and discussed. A consistent explanation of the independent experiments on stress-induced contact potential difference at metal surfaces is given.

This chapter discusses the origin of the surface specificity of adsorption energies and activation energies for surface reactions. It begins with the discussion of how the electronic structure of a surface determines the reactivity, and identifies the most important electronic structure parameters. The chapter provides a qualitative model of electronic factors in heterogeneous catalysis. The simplest model would be to use data of pure metal surfaces alone and not taking into account strain and ligand effects induced by the host material. The chapter concentrates only on the reactivity of transition metal surfaces and shows that trends in adsorption energies and activation energies from one system to the next can be understood in terms of variations in the local d DOS, in particular the d-band center. The chapter ends by indicating that similar concepts can be developed to understand trends in reactivity for transition metal compounds.