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Opis: Antimonene, the two-dimensional phase of antimony, appears in two distinct allotropes when epitaxially grown on Bi2Se3: the puckered asymmetric washboard (α) and buckled honeycomb (β) bilayer structures. As-deposited antimony films exhibit varying proportions of single α and β structures. We identify the conditions necessary for ordered, pure-phase growth of single to triple β-antimonene bilayers. Additionally, we determine their electronic structure, work function, and characteristic core-level binding energies, offering an explanation for the relatively large chemical shifts observed among the different phases. This study not only establishes a protocol for achieving a single β phase of antimonene but also provides key signatures for distinguishing between the different allotropes using standard spectroscopic and microscopic techniques.
Ključne besede: density functional theory, electronic band structure, topological insulators, work functions, scanning tunneling microscopy, atomic structure, antimony, angle-resolved photoemission spectroscopy, core level shifts
Objavljeno v RUNG: 20.03.2025; Ogledov: 1147; Prenosov: 10
Celotno besedilo (2,71 MB)
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Ključne besede: density functional theory, spin-resolved ARPES, electronic structure, topological insulators, 2D materials, antimonene
Objavljeno v RUNG: 18.07.2023; Ogledov: 3245; Prenosov: 5
Celotno besedilo (4,26 MB)
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Ključne besede: Carbon and nitrogen, General description, Hybrid functional, Near-edge X-ray absorption fine structure spectrum, Relevant features, Rydberg character, Theoretical spectra, Time dependent density functional theory
Objavljeno v RUNG: 19.01.2022; Ogledov: 3642; Prenosov: 0
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Opis: In this work, three surfaces, namely, Mg(0001), Mg(10 ̄1 0) and Mg(11 ̄2 0) are investigated by means of Density Functional Theory and Generalized Gradient Approximation first-principle calculations. The surfaces have been characterized in terms of their interlayer distances, surface energies, Projected Density of States and Surface Core Level Shifts. Contrary to what was found in previous studies based on Density Functional Theory-Local Density Approximation, the use of Generalized Gradient Approximation exchange correlation functional unravels the oscillatory behavior of both interlayer distances and Surface Core Level Shifts of Mg(10 ̄1 0). Moreover, the Projected Density Of States of un-reconstructed Mg(11 ̄2 0) exhibit the typical quantisation of electronic levels associated to a 2D-confinement of a 3D nearly-free electron gas, as observed in nano-wires, and a Peierls instability along the unconfined direction. Different possible reconstructions on Mg(11 ̄2 0) have then been investigated. In particular, it is found that the surface energy of (2X1) and (3X1) reconstructions is almost degenerate and lower than the surface energy of the unreconstructed Mg(11 ̄2 0) surface. Because of the quasi-degeneracy of surface energies, Mg(11 ̄2 0) surface should be composed by a combination of all the quasi degenerate phases.
Ključne besede: Density Functional Theory, first-principle calculations, Mg surface, Surface Core-Level Shift, surface relaxation, surface reconstruction
Objavljeno v RUNG: 04.07.2017; Ogledov: 7980; Prenosov: 2128
Celotno besedilo (1,77 MB)

Opis: Iron-phthalocyanine molecules deposited on the Au(110) reconstructed channels assemble into one-dimensional molecular chains, whose spatial distribution evolves into different structural phases at increasing molecular density. The plasticity of the Au channels first induces an ordered phase with a 5×5 symmetry, followed by a second long-range ordered structure composed by denser chains with a 5×7 periodicity with respect to the bare Au surface, as observed in the low-energy electron-diffraction (LEED) and grazing incidence X-ray diffraction (GIXRD) patterns. The geometry of the FePc molecular assemblies in the Au nanorails is determined by scanning tunneling microscopy (STM). For the 5×7 phases, the GIXRD analysis identifies a “4-3” rows profile along the [001] direction in the Au surface and an on-top FePc adsorption site, further confirmed by density functional theory (DFT) calculations. The latter also reveals the electronic mixing of the interface states. The chain assembly is driven by the molecule–molecule interaction and the chains interact with the Au nanorails via the central metal atom, while the chain–chain distance in the different structural phases is primarily driven by the plasticity of the Au surface.
Ključne besede: STM, LEED, DFT, density functional theory, phthalocyanine, Au(110), gold, surface
Objavljeno v RUNG: 13.10.2016; Ogledov: 6338; Prenosov: 0
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