Search results for "resolve"
showing 10 items of 258 documents
Test of band structure calculations for Heusler compounds by spin-resolved photoemission spectroscopy
2012
The electronic density of states of epitaxial thin films of the Heusler compound Co${}_{2}$MnGa is probed in situ by spin-resolved ultraviolet photoemission spectroscopy. The experiments reveal several characteristic features in the intensity spectrum and a clear Fermi edge signature. A high spin polarization of $\ensuremath{\simeq}\phantom{\rule{-0.16em}{0ex}}55%$ at the Fermi edge is followed by a sign change at the binding energy of $\ensuremath{\simeq}$0.8 eV. Corresponding calculations of the band structure and the photoemission spectrum were performed employing a spin-polarized relativistic Korringa-Kohn-Rostoker code. Good agreement between the experimental data and calculations was …
Orbital character variation of the Fermi surface and doping dependent changes of the dimensionality inBaFe2−xCoxAs2from angle-resolved photoemission …
2010
From a combination of high resolution angle-resolved photoemission spectroscopy and density functional calculations, we derive information on the dimensionality and the orbital character of the electronic states of ${\text{BaFe}}_{2\ensuremath{-}x}{\text{Co}}_{x}{\text{As}}_{2}$. Upon increasing Co doping, the electronic states in the vicinity of the Fermi level take on increasingly three-dimensional character. Both the orbital variation with ${k}_{z}$ and the more three-dimensional nature of the doped compounds have important consequences for the nesting conditions and thus possibly also for the appearance of antiferromagnetic and superconducting phases.
Néel Vector Induced Manipulation of Valence States in the Collinear Antiferromagnet Mn 2 Au
2020
The coupling of real and momentum space is utilized to tailor electronic properties of the collinear metallic antiferromagnet Mn2Au by aligning the real space Neel vector indicating the direction o...
Metal valence states inEu0.7NbO3,EuNbO3,andEu2Nb5O9by TB-LMTO-ASA band-structure calculations and resonant photoemission spectroscopy
1998
The electronic structures of ${\mathrm{Eu}}_{2}{\mathrm{Nb}}_{5}{\mathrm{O}}_{9},$ ${\mathrm{EuNbO}}_{3},$ and ${\mathrm{Eu}}_{0.7}{\mathrm{NbO}}_{3}$ have been investigated by photoemission and total-yield spectroscopy with synchrotron radiation, and in the case of ${\mathrm{Eu}}_{2}{\mathrm{Nb}}_{5}{\mathrm{O}}_{9}$ by tight-binding linear muffin-tin orbital (LMTO) band-structure calculations. A central question for reduced europium niobates is that of the valence of Eu and Nb. Both europium and niobium atoms can appear in different valence states so that various electronic configurations in the title compounds are possible. For this reason, the valence band was studied by the resonant Eu…
Dynamical Processes in Open Quantum Systems from a TDDFT Perspective: Resonances and Electron Photoemission
2015
We present a review of different computational methods to describe time-dependent phenomena in open quantum systems and their extension to a density-functional framework. We focus the discussion on electron emission processes in atoms and molecules addressing excited-state lifetimes and dissipative processes. Initially we analyze the concept of an electronic resonance, a central concept in spectroscopy associated with a metastable state from which an electron eventually escapes (electronic lifetime). Resonances play a fundamental role in many time-dependent molecular phenomena but can be rationalized from a time-independent context in terms of scattering states. We introduce the method of c…
Mechanism‐Dependent Modulation of Ultrafast Interfacial Water Dynamics in Intrinsically Disordered Protein Complexes
2018
Abstract The recognition of intrinsically disordered proteins (IDPs) is highly dependent on dynamics owing to the lack of structure. Here we studied the interplay between dynamics and molecular recognition in IDPs with a combination of time‐resolving tools on timescales ranging from femtoseconds to nanoseconds. We interrogated conformational dynamics and surface water dynamics and its attenuation upon partner binding using two IDPs, IBB and Nup153FG, both of central relevance to the nucleocytoplasmic transport machinery. These proteins bind the same nuclear transport receptor (Importinβ) with drastically different binding mechanisms, coupled folding–binding and fuzzy complex formation, resp…
On $L^p$ resolvent estimates for Laplace-Beltrami operators on compact manifolds
2011
Abstract. In this article we prove Lp estimates for resolvents of Laplace–Beltrami operators on compact Riemannian manifolds, generalizing results of Kenig, Ruiz and Sogge (1987) in the Euclidean case and Shen (2001) for the torus. We follow Sogge (1988) and construct Hadamard's parametrix, then use classical boundedness results on integral operators with oscillatory kernels related to the Carleson and Sjölin condition. Our initial motivation was to obtain Lp Carleman estimates with limiting Carleman weights generalizing those of Jerison and Kenig (1985); we illustrate the pertinence of Lp resolvent estimates by showing the relation with Carleman estimates. Such estimates are useful in the …
From Resolvent Estimates to Semigroup Bounds
2019
In Chap. 10 we saw a concrete example of how to get resolvent bounds from semigroup bounds. Naturally, one can go in the opposite direction and in this chapter we discuss some abstract results of that type, including the Hille–Yoshida and Gearhardt–Pruss–Hwang–Greiner theorems. As for the latter, we also give a result of Helffer and the author that provides a more precise bound on the semigroup.
Approximations of positive operators and continuity of the spectral radius III
1994
AbstractWe prove estimates on the speed of convergence of the ‘peripheral eigenvalues’ (and principal eigenvectors) of a sequence Tn of positive operators on a Banach lattice E to the peripheral eigenvalues of its limit operator T on E which is positive, irreducible and such that the spectral radius r(T) of T is a Riesz point of the spectrum of T (that is, a pole of the resolvent of T with a residuum of finite rank) under some conditions on the kind of approximation of Tn to T. These results sharpen results of convergence obtained by the authors in previous papers.
Electronic exchanges between adsorbed Ni atoms and TiO2(110) surface evidenced by resonant photoemission
2011
Abstract Nickel was deposited on stoichiometric TiO2(1 1 0) surface in the 0.02–2.1 equivalent monolayer (eqML) range and analyzed by means of photoemission and resonant photoemission. In the case of very low coverage (lower than 0.1 eqML), deposited nickel reacts with the surface through an electronic transfer from nickel atoms towards titanium ions. This exchange caused the filling of unoccupied Ti3d states leading to the increase of a peak in the TiO2 band gap. These states can be better characterized through resonant photoemission experiments at the Ti 3p → 3d absorption edge: for very low coverage, these states in the TiO2 band gap have resonant behavior of Ti3d electrons rather than N…