Search results for "ELECTRONIC STRUCTURE"
showing 10 items of 722 documents
First-principles comparative study of perfect and defective CsPbX3 (X = Br, I) crystals
2020
We thank R. Merkle for numerous fruitful discussions and G. Siegle for experimental assistance. This study was partly supported by the M-ERA-NET project SunToChem (EK). Calculations were performed using computational facilities of St. Petersburg State University and Max Planck Institute for Solid State Research. Open Access funding provided by the Max Planck Society.
Ab initiocalculations of theFcenters in MgF2bulk and on the (001) surface
2012
We present and discuss the results of atomic and electronic structure calculations of the F centers in MgF2 bulk and on the (001) surface. The calculations are based on the B3PW Hartree–Fock and density functional theory hybrid exchange-correlation functional. Most of the electronic density of a missing fluorine ion is localized in the bulk vacancy and a little bit less—in a surface vacancy. It is shown that the electronic F center is a deep donor. The lattice distortion and defect formation energy on the neutral (001) surface and in the bulk are also compared.
First principles calculations on CeO2 doped with Tb3+ ions
2019
This research was funded by the Latvian Council of Science (under the grant project lzp-2018/1-0147). Authors thank W. Chueh, J. Serra, R. Merkle, A. Popov for fruitful discussions.
Hydrogen adsorption on the ZnO $(1\bar{1}00)$ surface: ab initio hybrid density functional linear combination of atomic orbitals calculations
2014
Hydrogen atoms unavoidably presented in ZnO samples or thin films during their synthesis considerably affect electrical conductivity. Results of first principles hybrid functional linear combination of atomic orbitals calculations are discussed for hydrogen atoms incorporated in bulk or adsorbed upon non-polar ZnO (1¯ 100) surfaces. The energy of H incorporation, atomic relaxation, electronic density redistribution and modification of the electronic structure are compared for both surface adsorption and bulk absorption. It is shown that hydrogen forms a strong bonding with the surface O ions (Eads = 2.7eV) whereas its incorporation into bulk is energetically quite unfavorable. Hydrogen adso…
Self-Passivating Edge Reconstructions of Graphene
2008
Planar reconstruction patterns at the zigzag and armchair edges of graphene were investigated with density functional theory. It was unexpectedly found that the zigzag edge is metastable and a planar reconstruction spontaneously takes place at room temperature. The reconstruction changes electronic structure and self-passivates the edge with respect to adsorption of atomic hydrogen from molecular atmosphere.
Electronic and Magnetic Properties of Ligand-Free FePt Nanoparticles
2005
Ligand-free FePt nanoparticles are prepared in densely packed arrays (see Figure) under ultrahigh vacuum conditions, in which oxygen and hydrogen plasmas are used to remove the organic shells that are present after particle synthesis. The electronic structure and magnetic properties of the “bare”, face-centered-cubic FePt particles are presented. Applications in high-density magnetic data recording are foreseen.
Electronic Structure Changes across the Metamagnetic Transition in FeRh via Hard X-Ray Photoemission
2012
International audience; Stoichiometric FeRh undergoes a temperature-induced antiferromagnetic (AFM) to ferromagnetic (FM) transition at similar to 350 K. In this Letter, changes in the electronic structure accompanying this transition are investigated in epitaxial FeRh thin films via bulk-sensitive valence-band and core-level hard x-ray photoelectron spectroscopy with a photon energy of 5.95 keV. Clear differences between the AFM and FM states are observed across the entire valence-band spectrum and these are well reproduced using density-functional theory. Changes in the 2p core levels of Fe are also observed and interpreted using Anderson impurity model calculations. These results indicat…
The electronic structure of zircon-type orthovanadates: Effects of high-pressure and cation substitution
2012
The electronic structure of four ternary-metal oxides containing isolated vanadate ions is studied. Zircon-type YVO4, YbVO4, LuVO4, and NdVO4 are investigated by high-pressure optical-absorption measurements up to 20 GPa. First-principles calculations based on density-functional theory were also performed to analyze the electronic band structure as a function of pressure. The electronic structure near the Fermi level originates largely from molecular orbitals of the vanadate ion, but cation substitution influence these electronic states. The studied ortovanadates, with the exception of NdVO4, undergo a zircon-scheelite structural phase transition that causes a collapse of the band-gap energ…
Ionization potential of aluminum clusters
1998
Structure, electronic structure, and ionization potential of aluminum clusters of 2–23 atoms are studied with a total energy method based on the density-functional theory. The calculated adiabatic ionization potentials agree remarkably well with the data from threshold photoionization measurements. The analysis of results gives insight into hybridization effects in the smallest clusters as well as reveals certain clusters that exhibit a clear jellium-type shell structure. An explanation of the experimental results in the size region of 12–23 atoms is given in terms of coexisting, competing icosahedral, decahedral, and fcc-based clusters. @S0163-1829~98!00228-8#
Differences and Similarities between the Isotypic AntimonidesMFe1−xSb, ScCo1−xSb, andMNiSb (M=Zr, Hf)
1999
The new antimonides MFe{sub 1{minus}x}Sb can be synthesized by arc-melting of M, Fe, and MSb{sub 2} (M = Zr, Hf). All title compounds crystallize in the TiNiSi structure type (space group Pnma, Z = 4). The lattice parameters of the new phases of MFe{sub 1{minus}x}Sb, as obtained from the bulk samples of the nominal compositions MFeSb, are a = 681.4(1) pm, b = 417.87(7) pm, c = 740.3(1) pm for ZrFe{sub 1{minus}x}Sb and a = 674.0(1) pm, b = 412.0(2) pm, c = 729.7(2) pm for HfFe{sub 1{minus}x}Sb. Under the reaction conditions used, the occupancy factors of the iron position content of ZrFe{sub 1{minus}x}Sb does not exceed 68(1)% (i.e., x = 0.32(1)). Extended Hueckel calculations, performed on …