Arrigo Calzolari

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Attempts to resolve the energy-level structure of single DNA molecules by scanning tunnelling spectroscopy span over the past two decades, owing to the unique ability of this technique to probe the local density of states of objects deposited on a surface. Nevertheless, success was hindered by extreme technical difficulties in stable deposition and(More)
Although generally ascribed to the presence of defects, an ultimate assignment of the different contributions to the emission spectrum in terms of surface states and deep levels in ZnO nanostructures is still lacking. In this work we unambiguously give first evidence that zinc vacancies at the (1010) nonpolar surfaces are responsible for the green(More)
Using first principles calculations based on density functional theory and a coupled finite-fields/finite-differences approach, we study the dielectric properties, phonon dispersions and Raman spectra of ZnO, a material whose internal polarization fields require special treatment to correctly reproduce the ground state electronic structure and the coupling(More)
The growth of films of [H2B(pz)2]Fe(ii)(bpy) on Au(111) is characterized from the bilayer film to multilayer film regime. Scanning tunneling microscopy shows a transition from a well-ordered, uniform bilayer film to a poorly-ordered film at larger thicknesses. Previous local tunneling spectroscopy and conductance mapping in bilayer films permit the(More)
We report on a spectroscopic multitechnique approach to study the metal/radical spinterface formed by a perchlorinated trityl radical derivative and either gold or silver. The spectroscopic fingerprint of their paramagnetic properties could be determined by comparison with their diamagnetic precursor and by DFT calculations. Thanks to the presented(More)
The electronic structure constitutes the fundamentals on which a reliable quantitative knowledge of the electrical properties of materials should be based. Here, we first present an overview of the methods employed to elucidate the ground-state electronic properties, with an emphasis on the results of Density Functional Theory (DFT) calculations on selected(More)
We study the electronic and transport properties of artificial Au atomic chains on a NiAl(110) surface template using state-of-the-art first principles calculations. Au chains display remarkable one-dimensional electronic properties that can be tuned by the selective adsorption of small molecules: a single CO group is shown to modulate the electronic wave(More)
The synthesis of ZnO porous nanobelts with high surface-to-volume ratio is envisaged to enhance the zinc oxide sensing and photocatalytic properties. Yet, controlled stoichiometry, doping and compensation of as-grown n-type behavior remain open problems for this compound. Here, we demonstrate the effect of residual sulfur atoms on the optical properties of(More)
Acknowledgments First I would like to thank my supervisors Prof. Stefano Baroni and Dr. Arrigo Calzolari for their constant guidance, encouragement and continuous support through the years of my study at SISSA. Prof. Baroni has introduced me the theoretical background of this thesis, and he has inspired me with wonderful ideas in the algorithm development.(More)
Using first principles calculations, we predict a complex multifunctional behavior in cobalt bis(dioxolene) valence tautomeric compounds. Molecular spin-state switching is shown to dramatically alter electronic properties and corresponding transport properties. This spin state dependence has been demonstrated for technologically relevant coordination(More)