We present a sampling method for Brillouin-zone integration in metals which converges exponentially with the number of points, without loss precision normal broadening techniques. The scheme is based on smooth approximants to \ensuremath{\delta} and step functions are constructed give exact result when integrating polynomials prescribed degree. In applications simple-cubic tight-binding band as well structures simple transition metals, we demonstrate significant improvement over existing...

The total energy of the 3d transition metals is calculated as a function volume in each six different crystal structures. calculations employ local-density-functional scheme and full-potential linear muffin-tin orbitals method. Both self-consistent non-self-consistent Harris-Foulkes are shown connection made between these simpler tight-binding classical models interatomic forces. energy-volume relations may serve database construction such empirical schemes.

We show, using a proposed oxygen-defect structure for ${\mathrm{YBa}}_{2}{\mathrm{Cu}}_{3}{\mathrm{O}}_{7\ensuremath{-}x}$ and tight-binding model based on density-functional calculations, that the distribution of holes between planes (fragmented) chains causes jumps plateaus hole counts in as function nonstoichiometry, $x$. These features can be correlated with occurrence antiferromagnetic well 60- 90-K superconducting phases. Our findings are supportive view count is controlling parameter...

We demonstrate a kinetic Monte Carlo simulation tool, based on published data using first-principles quantum mechanics, applied to answer the question: under which conditions of stress, temperature, and nominal hydrogen concentration does presence in iron increase or decrease screw dislocation velocity? Furthermore, we examine hydrogen-induced shear localization is likely occur. Our simulations yield quantitative velocity ranges within large gradient as function expected be observed thereby...

$(1\ifmmode\times\else\texttimes\fi{}1)$ and $(2\ifmmode\times\else\texttimes\fi{}1)$ reconstructions of the (001) $\mathrm{Sr}\mathrm{Ti}{\mathrm{O}}_{3}$ surface were studied using first-principles full-potential linear muffin-tin orbital method. Surface energies calculated as a function $\mathrm{Ti}{\mathrm{O}}_{2}$ chemical potential, oxygen partial pressure ${p}_{{\mathrm{O}}_{}2}$and temperature. The unreconstructed surfaces found to be energetically stable for many conditions...

We use the local spin-density approximation in density-functional theory to study electronic structure of ${\mathrm{TiO}}_{2}$ and its (110) stoichiometric surface, as well ${\mathrm{Ti}}_{2}{\mathrm{O}}_{3}$ reduced which are examples ${\mathrm{TiO}}_{2},$ order address question how donated electrons distributed among previously unoccupied Ti $3d$ states. conclude that, whereas a split-off band probably leads Mott-Hubbard insulating behavior, picture itinerant approximately one-electron...

First-principles calculations of the $\ensuremath{\Sigma}5(310)[001]$ symmetric tilt grain boundary in Cu with Bi, Na, and Ag substitutional impurities provide evidence that phenomenon Bi embrittlement boundaries electronic effects do not play a major role; on contrary, is mostly structural or ``size'' effect. Na predicted to be nearly as good an embrittler whereas does embrittle agreement experiment. While we reject prevailing view ``electronic'' (i.e., charge transfer) are responsible for...

The origin of the relative stability cubic, tetragonal, and monoclinic phases zirconia $(\mathrm{ZrO}{}_{2})$ is investigated. To obtain accurate energies we adopt a new all-electron bandstructure approach within local density approximation, based on muffin tin orbitals. We also develop self-consistent tight-binding model with which to study for different structures. enables us analyze ab initio experimental phase stabilities in terms ionic versus covalent effects, including polarization...

Abstract We use the local density approximation to functional theory re-examine well-known ‘theoretical strength’ of metals. This is done by calculating ideal twin stress in five b.c.c. transition metals, and Ir, Cu Al. leads us a first-principles, quantum-mechanical confirmation Frenkel model plasticity which has previously been thought have too oversimplified be realistic. discuss this result light Peierls—Nabarro relate it deformation behaviour group-5 group-6 also include general...

Brightness traces of the solidification highly undercooled Ta and Re droplets processed in an ultrahigh vacuum drop tube give evidence two successive phase transformations. First-principles calculations structural stability these metals are developed order to appreciate possibilities obtaining alternative phases. Some prototype transition metal crystal structures were examined fcc for A15 possible candidates observed metastable Good agreement is obtained between theoretical experimental...

Our ab initio study suggests that boron segregation to the Sigma 5(310)[001] grain boundary should strengthen up 1.5 ML coverage (15.24 at/nm^2). The maximal effect is observed at 0.5 and corresponds atoms filling exclusively interstices. In copper bulk, B causes significant distortion both in interstitial regular lattice sites for which are either too big or small. compensated large extent when substitutional combine together form a strongly bound dumbell. prediction impurities appear...

Abstract Bearing steels are complex materials composed of an iron matrix and a well defined precise amount several alloying elements.
In order to improve sustainability circularity, there is tendency increase the utilisation scrap material for their production.
The variability composition has direct impact on properties final steels: There less control due possible presence larger amounts tramp elements.
One way study effect elements by using universal machine...

We describe an empirical, self-consistent, orthogonal tight-binding model for zirconia, which allows the polarizability of anions at dipole and quadrupole levels crystal field splitting cation d orbitals. This is achieved by mixing orbitals different symmetry on a site with coupling coefficients driven Coulomb potentials up to octapole level. The additional forces atoms due self-consistency polarizabilities are exactly obtained straightforward electrostatics, analogy Hellmann-Feynman theorem...

Phase stability in the Ni-Al binary system is investigated using linear muffin-tin orbitals total energy (LMTO) calculations. They provide energies for different existing compounds and, Connolly-Williams inversion, many-body interactions occurring FCC and BCC lattices. These are used conjunction with cluster variation method (CVM) to calculate phase diagram. The computed diagram agrees very well experimental one.

We present the results of a phase stability study in Ni-Ti system. In particular, formation energies three Ni${\mathrm{Ti}}_{2}$, NiTi, and ${\mathrm{Ni}}_{3}$Ti compounds have been calculated using full potential linear-muffin-tinorbital method. The correlation between electronic concentration crystal structure is interpreted terms filling bonding states for compound. Two sets effective cluster interactions are determined allowing us to include bcc- fcc-based solid solutions analysis....

1. Strains of Escherichia coli were obtained containing either the AraE or AraF transport system for arabinose. AraE+,AraF- strains effected energized accumulation and displayed an arabinose-evoked alkaline pH change indicative arabinose-H+ symport. In contrast, AraE-,AraF+ accumulated arabinose but did not display H+ 2. The ability different sugars their derivatives to elicit sugar-H+ symport in AraE+ was examined. Only L-arabinose D-fucose good substrates, only inducer. 3. Membrane...

Abstract This article reviews some recent progress in the derivation of physical models for calculating behaviour defects transition metals by atomistic simulation. It has long been recognised that it is necessary to go beyond assumption pair-wise interactions, but this only recently achieved with advent simplified which take account electron gas. For d-band metals, tight-binding model a useful picture and can be applied at various levels approximation. The simplest these second-moment...

The Royal Society Scientific Discussion Meeting ‘The challenges of hydrogen and metals’ was held in Carlton House Terrace, London, UK, on 16–18 January 2017. This is the introductory article to discussion meeting issue which includes contributed papers seven papers. Here, we introduce motivation hold give a brief overview contents. We conclude with acknowledgements. part themed metals’.

We investigate the ability of local density approximation (LDA) in functional theory to predict near-edge structure electron energy-loss spectroscopy dipole approximation. include screening core hole within LDA using Slater's transition state theory. find that anion K-edge threshold energies are systematically overestimated by 4.22±0.44 eV twelve metal carbides and nitrides rock-salt (B1) structure. When we apply this `universal' many-electron correction spectra calculated LDA, quantitative...

The stability of Hume–Rothery's electron phases is studied using modern bandstructure techniques. For these alloys, empirical evidence has shown a strong correlation between the number valence electrons per atom and adopted crystal structure. generally accepted explanation traces phenomenon to prominent structure in density states which arises when free–electron Fermi sphere encounters Bragg planes at surface Brillouin zone. By applying rigid band model on basis functional theory archetypal...