The electronic structure of the uranyl ion

Polarized single crystal absorption spectra at 4·2 K are reported for CsUO₂(NO₃)₃ and NaUO₂(CH₃COO)₃. Natural and magnetic circular dichroism and Zeeman effect measurements have been made. Measurements have also been made on crystals containing U¹⁸O₂ ²⁺. In the portion of the spectrum between 21 000 and 30 000 cm^-1 seven electronic states have been identified in both CsUO₂(NO₃)₃ and NaUO₂(CH₃COO)₃. In the majority of cases the symmetry of the excited states has been assigned.     

The electronic structure of ordered Cu3Au(001)

The electronic structure of the (001) face of ordered Cu₃Au was studied using synchrotron radiation at BESSY, in the photon energy range 22–80 eV. The Cu 3d-derived bands in Cu₃Au look like the foldedd-bands of fcc Cu metal. Three Au 5d-derived bands were observed at 5.0, 6.1 and 7.0 eV below the Fermi level, which showed no dispersion with change in photon energy. The Cu 3d- and the Au 5d-derived bands are found to be separated in energy. We have calculated self-consistent energy bands along the (001) direction using the fully relativistic LMTO method. Comparison of these bands with those experimentally determined shows good agreement. From the calculated bands along –X the direction dependent densities of states were determined, which give a consistent account for the non-dispersive Au-bands.     

Instability,intermixing and electronic structure at the epitaxial LaAlO3/SrTiO3(001) heterojunction

The question of stability against diffusional mixing at the prototypical LaAlO₃/SrTiO₃(001) interface is explored using a multi-faceted experimental and theoretical approach. We combine analytical methods with a range of sensitivities to elemental concentrations and spatial separations to investigate interfaces grown using on-axis pulsed laser deposition. We also employ computational modeling based on the density function theory as well as classical force fields to explore the energetic stability of a wide variety of intermixed atomic configurations relative to the idealized, atomically abrupt model. Statistical analysis of the calculated energies for the various configurations is used to elucidate the relative thermodynamic stability of intermixed and abrupt configurations. We find that on both experimental and theoretical fronts, the tendency toward intermixing is very strong. We have also measured and calculated key electronic properties such as potential energy gradients and valence band discontinuity at the interface. We find no measurable electric field in either the LaAlO₃ or SrTiO₃, and that the valence band offset is near zero, partitioning the band discontinuity almost entirely to the conduction band edge. Significantly, we find it is not possible to account for these electronic properties theoretically without including extensive intermixing in our physical model of the interface. The atomic configurations which give the greatest electrostatic stability are those that eliminate the interface dipole by intermixing, calling into question the conventional explanation for conductivity at this interface—electronic reconstruction. Rather, evidence is presented for La indiffusion and doping of the SrTiO₃ below the interface as being the cause of the observed conductivity.     

Crystal and molecular structure of N-(p-nitrobenzylidene)-3-chloro-4-fluoroaniline

The crystal structure of N-(p-nitrobenzylidene)-3-chloro-4-fluoroaniline (II) has been determined by X-ray structure analysis. This belongs to a class of benzylidene anilines. The structure was solved by direct method. The molecular packing of the non-planar molecules are held by Van der Waals and F…H7, O…Cl, F…F and N…H interactions.     

第一性原理研究BaTiO3(001)表面的电子结构

在密度泛函理论的基础上,采用平面波赝势方法计算了立方相BaTiO3(001)表面的电子结构.结构优化表明最表层原子都向体内弛豫,且金属原子弛豫幅度最大,同时各层层间距变化呈交错分布.对两种表面结构的总能计算发现TiO:表面稳定性比BaO表面弱,一方面是由于TiO2表向结构中存在O-2p表面态,使价带和导带中电子态向高能区域偏移.另一方面,TO2表面附近Tj-O共价键存在强弱差异,有利于发生表面吸附.而在BaO表面结构中,最表层BaO的存在消除了这种差异,因而其表面稳定性较强.     

The electronic structure of SrTiO3 and some simple related oxides (MgO,Al2O3, SrO,TiO2)

The valence band density of states (VBDOS) of the insulating oxides SrTiO₃, TiO₂, SrO, MgO and Al₂O₃ obtained by X-ray photoelectron spectroscopy (XPS), are reported. Qualitatively, the VBDOS of these oxides are similar to one another. The XPS results are compared with results from soft X-ray emission spectroscopy (XES), ultraviolet photoemission spectroscopy (UPS), and theoretical calculations. There are some differences (in particular for TiO₂) between the XES and XPS results, which are probably due to matrix element effects enhancing different features of the VBDOS in the two techniques. The XPS results definitively establish the position of the O 2s level, which had been erroneously assigned in previous low-energy UPS measurements. Cluster-type calculations are demonstrated to give a reasonable representation of the VBDOS for the oxides.     

Dynamical properties and electronic structure of (LaLi)TiO3 conductors

A computer simulation by a molecular dynamics method is performed to study the properties of structure and Li ion diffusion in La_4/3???x Li (LaLi)TiO₃ ;LLTO;Li ion conductors;Superionic conductors;Perovskite;Off-site;Electronic structureA computer simulation by a molecular dynamics method is performed to study the properties of structure and Li ion diffusion in La_{4/3 − x} Li Ti₂O₆ =(LaLi)TiO₃ =LLTO, which is the perovskite-type Li ion conductor. In the low Li concentration, Li ions conduct a two-dimensional motion, while Li ions diffuse a three-dimensional motion in the high Li ion concentration. The partial distribution function for Li–Ti and the diffusion paths of Li ions suggest that Li ions stay for a long time at off-site positions, which are 2.7? away from a body-centered Ti ion. The Li ion concentration dependence to the conductivity σ is in approximate agreement with experiments. The energy band dispersion and the density of states are calculated using the linear-muffin-tin-orbital method. The energy contour map shows the stable position of Li ions is off center of the vacant La sites. Both calculations suggest that the stable position of Li ions is off center of the vacant La sites. Paper presented at the 11th EuroConference on the Science and Technology of Ionics, Batz-sur-Mer, Sept. 9–15, 2007.     

Multiple-photon ir excitation of electronic states of OsO4 molecule

Basic experimental characteristics of collisionless luminescence of OsO₄ molecule excited by pulsed ir laser radiation are presented. The theoretical model of the process is developed and a comparison with experiment is carried out both for one-frequency and two-frequency ir excitation. From such comparison information is obtained on the fraction of molecules excited by laser radiation as well as on the spectroscopic characteristics of highly excited states.     

Stability and electronic structure studies of LaAlO_3/SrTiO_3 (110) heterostructures

The first-principles calculations are employed to investigate the stability, magnetic, and electrical properties of the oxide heterostructure of LaAlO3/SrTiO3(110). By comparing their interface energies, it is obtained that the buckled interface is more stable than the abrupt interface. This result is consistent with experimental observation. At the interface of LaAlO3/SrTiO3(110) heterostructure, the Ti–O octahedron distortions cause the Ti t2 gorbitals to split into the twofold degenerate dxz/dyz and nondegenerate dxy orbitals. The former has higher energy than the latter. The partly filled two-fold degenerate t2 gorbitals are the origin of two-dimensional electron gas, which is confined at the interface. Lattice mismatch between LaAlO3 and SrTiO3leads to ferroelectric-like lattice distortions at the interface, and this is the origin of spin-splitting of Ti 3d electrons. Hence the magnetism appears at the interface of LaAlO3/SrTiO3(110).     

The electronic structure of Cs adsorbed on Mo(111)

The main loss observed in an ELS study of Cs adsorbed on Mo(100) is described as an interband transition with initial and final states in the adsorbate. This interpretation is preferred to that involving the plasmon excitation mechanism observed for Cs on Cu(111) in the coverage range where the Cs has a metallic nature. The occurence of this transition is assumed to be related to the substrate effect.     

The surface electronic structure of (100) centered tetragonal copper

We present a theoretical investigation of the surface electronic structure for the (100) surface of centered tetragonal copper. The calculated band structure and k_- and layer-resolved densities of states for the surface and bulk are compared with corresponding quantities obtained for the face centered cubic (fcc) structure. We have found a surface state at about 5 eV below the Fermi level which is splitted off the bulk s-d band for both the tetragonal and the fcc structure. Furthermore, we have calculated the normal photoemission spectra within the one-step approach. The direct transition model explains all features of available experimental data. Particularly, we can conclude that the invisibility of the surface state for the fcc structure in most of the photoemission experiments is driven by the final states.     

First-principles study of electronic structure and optical properties of Sr(Ti,Zr)O3

Electronic and optical properties of Sr(Ti,Zr)O₃ crystals in the cubic (Pm-3m) and tetragonal (I4/mcm) phase were calculated by the first-principles calculations using the density functional theory and the local density approximation. The band structure of cubic and tetragonal phases show an indirect band gap at (R-Γ) point and at (M-Γ) point in the Brillouin zone, respectively. The linear photon-energy dependent dielectric functions and some optical properties such as the absorption coefficient, energy-loss function and reflectivity are calculated for both phases. The optical properties of tetragonal phase of Sr(Ti,Zr)O₃ were investigated by theoretical methods for the first time. We have also made some comparisons with the available related experimental and theoretical data.     

The electronic structure of the one-dimensional tetrahedrally distorted porphyrinatonickel (II) system

The band structure of a saddle-shaped porphyrinatonickel (II) backbone is investigated by a semiempirical INDO crystal orbital approach at an interdeck separation of 3.446 Å. The low-dimensional oxidized material (injected holes) belongs to a group of organic metals where Coulomb correlations cannot be neglected in comparison to one-electron tight-binding interactions.     

First-principle studies on the electronic structure of Fe3O4(110) surface

The first-principle was employed to study the six possible models for the Fe₃O₄(110) surface, namely the AB-terminated surface (AB model), the AB-terminated with Fe_A vacancy (AB-Fe_A vac model), the AB-terminated with Fe_B vacancy (AB-Fe_B vac model), the B-terminated surface (B model), the B-terminated surface with Fe_B vacancy (B-Fe_B vac model) and the B-terminated surface with O vacancy (B-O vac model). The stability, the electronic structure and the magnetic properties of the six surface models were also calculated. The results predict that the B-O vac model is more stable than other types of surface models. The half-metallic property remain in the AB and B models, while the other four surface models exhibit metallic properties. At the same time, the AB, AB-Fe_A vac, AB-Fe_B vac, B and the B-Fe_B vac models have ferrimagnetic properties, while the B-O vac model has antiferromagnetic property.      

The electronic structure and crystal field of RPt3Si (R=Pr, Nd, Sm) compounds

First-principles calculations based on density-functional theory (DFT) were performed on RPt₃Si (R=Pr, Nd, Sm) for the first time. The electronic density of states (DOS) and bonding properties were studied using relativistic full-potential APW plus local orbitals calculations. The crystal-field (CF) splitting was derived for NdPt₃Si and SmPt₃Si by fitting the temperature-dependent magnetic susceptibility. The starting estimate of the CF parameters for fitting procedure was obtained from first-principles calculations based on DFT.     

On the trimer approximation to the theory of Cs2(TCNQ)3 electronic structure

The electronic states of the crystalline Cs₂(TCNQ)₃ are studied under an assumption that the crystal consists of isolated trimers of TCNQ molecules occupied by two unpaired electrons. The Hamiltonian is a modified Hubbard Hamiltonian. The theory is related to the experimental data. A direction of necessary extension of the theory is discussed.     

The electronic structure of cobalt(II) phthalocyanine adsorbed on Ag(111)

The electronic states of submonolayers and multilayers of cobalt(II) phthalocyanine (CoPc) adsorbed on Ag(111) were examined with photoelectron spectroscopy to obtain insight into the details of the substrate–adsorbate interaction. UV photoelectron spectroscopy (UPS) reveals the presence of two interaction-related valence states in the direct vicinity of the Fermi edge, in agreement with previous DFT calculations. X-ray photoelectron spectra indicate that the substrate–adsorbate interaction results in transfer of electron density from the substrate to the Co(II) ion. Substantial changes in the Co 2p multiplet structure, a spectral pattern induced by the open-shell character of the central Co(II) ion, indicate a complete quenching of the molecular spin. While pristine CoPc molecules are paramagnetic with S = 1/2, molecules in direct contact to the Ag(111) substrate appear to be in a diamagnetic state.