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The structure and defects of cobalt doped tin dioxide were investigated using the density functional theory and empirical force fields. The computations were carried out for different concentrations of cobalt (3.125, 6.25, 12.5, and 18.75 at%). It is shown that at the cobalt doping less than 4 at%, the oxygen vacancy occurs at the place of the oxygen bounded by cobalt. The electron density of states is computed when cobalt creates the states near a conduction band. By further increase in the cobalt concentration, the order of the structure begins to destroy.

The method is developed for calculation of electronic properties of an ensemble of metal nanoclusters with the use of cluster perturbation theory. This method is applied to the system of gold nanoclusters. The Greens function of single nanocluster is obtained by ab initio calculations within the framework of the density functional theory, and then is used in Dyson equation to group nanoclusters together and to compute the Greens function as well as the electron density of states of the whole ensemble. The transition from insulator state of a single nanocluster to metallic state of bulk gold is observed.

In high-pressure phase transition experiments, the crystal structure of the intermediate phase in some phase transitions is difficult to successfully measure due to the limitations of the experimental conditions. The absence of crystal structure data for the intermediate phase also makes it difficult to calculate the pressure point from the intermediate phase to the new phase by the traditional thermodynamic criterion in theoretical simulations. The Conch Criterion is employed by us to successfully verify the phase transition points by observing the reverse shifts of the DOS (electron density of states) curves for the new phase of Cu2S, PbS, PbSe and PbTe, which breaks through the constraints of the traditional criterion and realizes tracing the source of the phase transition in theoretical calculations.

The experimental determination of the superconducting transition requires the observation of the emergence of zero-resistance and perfect diamagnetism state. Based on the close relationship between superconducting transition temperature (Tc) and electron density of states (DOS), we take two typical superconducting materials Hg and ZrTe3 as samples and calculate their DOS versus temperature under different pressures by using the first-principle molecular dynamics simulations. According to the analysis of the calculation results, the main contributors that induce superconducting transitions are deduced by tracing the variation of partial density of states near Tc. In particular, the microscopic mechanism of pressure increasing Tc is further analyzed., Comment: 18 pages, 4 figures

The magnetic moment, lattice parameter and atom fraction coordinates for Ce 3 Co 29 Si 4 B 10 are calculated by the first-principles GGA+U method, and the results indicate that the calculated and experimental values are basically accordant when U =2.6 eV. We study the interaction effect and orbital hybridization between Co and Ce atoms. The projected density of states at U =2.6 eV which provided by Co-2c, Ce-2b and Ce-4d sites are contrasted with else U values. Meanwhile the electron density of states for different sites and the distance between various atoms are exhibited. In addition, the thermodynamic properties of Ce 3 Co 29 Si 4 B 10 are evaluated by using a series of interatomic pair potentials.

A Density Functional Theory (DFT) based computation was conducted to study the electronic band structure, electron density of states (DOS), integrated DOS and partial DOS of LiFeP, a new iron pnictide superconductor, using Generalized Gradient Approximation (GGA) with ultrasoft pseudopotentials. The dominance of 3s state of ‘P’ in the region far below the Fermi level and thereof 3d state of ‘Fe’ near the Fermi level and also of ‘Li’ above the Fermi level are seen. The overlapping of bands near the Fermi level shows the metallic nature of LiFeP.

The many body quantum dynamical evaluation of double time thermodynamic electron Green’s functions followed by generalized electron density of states (EDOS) is used to study the superconducting gap (SG). The dependence of EDOS on defects, anharmonicity and electron-phonon interactions makes the problem quite complicated and challenging but furnishes the more realistic grounds to study the SG both in conventional and high temperature superconductors (HTS). For simplicity, only electron-phonon interaction has been taken up to evaluate the intricate integral to enumerate the SG for representative cuprate HTS: YBa2Cu3O7-δ and results show 2Δ/kBTc ⋍ 7.2.

Using density functional theory calculations, we have investigated the adsorption of Na on pristine and N-substituted defective graphene sheets (graphitic, pyridinic, and pyrrolic structures) and explored their application in Na-ion batteries. The adsorption energy and the charge transfer of Na on the various types of sheet were calculated. The effects of N-substitution were also studied by electronic structure analysis, including the total electronic density of states, partial electron density of states, and charge density differences. The results show that electron-rich structures have a negative influence on Na binding, while electron-deficient structures are beneficial. The Na storage capacities of different sheets were evaluated by optimizing multiple Na atom adsorbed structures. We found that more Na atoms can be stored on electron-deficient sheets, making them promising for practical application as electrode materials in Na-ion batteries.

We investigate the rectification and negative differential effects of full-counting statistics of conjugate thermal spin transport in a spin Seebeck engine. The engine is made by an electron/magnon interface diode driven by a temperature bias, of which the scaled cumulant generating function is formulated in the framework of nonequilibrium Green's function. The strongly fluctuating interfacial electron density of states induced by quantum dot is responsible for these intriguing properties. This work is relevant for designing efficient spin caloritronic engine and can broaden our view in nonequilibrium thermodynamics and the nonlinear phenomenon in quantum transport system., 10 pages, 4 figures

The geometric and electronic structures of Fe islands on MgO film layers were studied with scanning tunneling microscopy and spectroscopy. The MgO layers were grown on a Nb-doped single crystal SrTiO 3 (100) surface. Deposited Fe atoms aggregate into islands, the height and diameter of which are about 2.5 and 9.4 nm respectively. Fe islands modify the electronic structure of MgO surface; a ring type depression in the scanning tunneling microscope topography appears by lowered local electron density of states around Fe islands. We find that adsorbed Fe atoms reduce the gap states of MgO layers around Fe islands, which is attributed to the reason for the depletion of the electronic density of states.

The electronic, magnetic, and optical properties of TbN and ErN nanolayers in the presence of spin orbit coupling using density functional theory using the WIEN2k package are investigated. The stable phase of TbN and ErN bulk using generalized gradient approximation (GGA) approach is studied. The total and partial electron density of states of ErN and TbN nanolayers with two different thicknesses in ferromagnetic phase within GGA and Engel–Vosko GGA (GGA_EV) approaches is calculated. The total and local magnetic moments of these nanolayers are studied. The calculated magnetic moment at Er atomic position of ErN nanolayer is larger than the corresponding value at Tb atomic position of TbN nanolayer. Furthermore, the real and imaginary parts of the dielectric function and the reflectivity and absorption spectra of these nanolayers within GGA_EV approach are studied.

Structural, electronic, mechanical, thermodynamic and thermoelectric properties of Alkaline fluroperovskites ACdF3(A[Formula: see text]=[Formula: see text]K, Rb, Cs) have been explored using the FP-LAPW method from the perspective of density functional theory (DFT) as employed in the Wien2k package within the generalized gradient approximation (GGA) as well as the local spin density approximation (LSDA). The volume optimization calculations of these materials agree well with experimental as well as available theoretical values. From the energy dispersion curves as well as DOS plots, all the investigated alkali fluroperovskites are found to have an indirect bandgap in [Formula: see text]-M direction using both approximations. The second-order elastic constants as well as mechanical properties such as Young’s modulus, shear modulus, density, anisotropic factor, B/G[Formula: see text] ratio are also computed for these materials. In order to study the thermal and vibrational effects on the studied fluroperovskites, we have employed the quasi-harmonic Debye model that uses a set of energy versus volume calculations. The effects of temperature as well as pressure on the structural parameters are also studied using the non-equilibrium Gibbs function. The transport properties of these perovskites have been investigated using BoltzTrap Code. Comparatively, a good figure of merit of these compounds reveals their possible use in thermoelectric applications.

We present a systematic first principles density functional theory (DFT) based study of the (020) surface of α-plutonium using the projector-augmented-wave formalism as implemented in the Vienna Ab Initio Simulation Package (VASP). The surface was modeled by a periodic slab geometry comprised of anti-ferromagnetic atomic layers, with a thickness of up to ten atomic layers. The total and cohesive energies indicate a monotonically decreasing and increasing slope to the bulk values, respectively. The surface energies, in contrast to the work functions, exhibit a significant oscillatory pattern indicating persistent quantum size effects and possible magnetic frustration as well as other effects. The 5f electron density of states indicates progressive delocalization with increasing slab thickness.

Understanding the mechanism of C–C bond cleavage on the surface of a catalyst is central to the optimization of several reactions in the petrochemical industry. In this study, first-principles density functional theory calculations were performed to examine the adsorption properties, electronic structures, and energies of C–C bond scission in ethylidyne (CCH3) adsorbed on the (111) and (100) surfaces of Pd, and the results were compared with those of Pt. On the basis of the analyses of the electron density of states (DOS), partial charge density, and wave functions, it appears that on the adsorption of C–C, two types of bonding orbitals, namely, σC–C and πC–C, are formed. On both the low-index surfaces of Pd, the perpendicular adsorption of CCH3 was found to be the most stable configuration. Compared with the adsorption on the Pd(111) surface, the adsorption on the Pd(100) surface was less stable. On the contrary, the adsorption energies on the (111) and (100) surfaces of Pt were almost the same. Neverthe...

A theoretical study of NO2 sensing capability of MoS2 doped with elements including Si and Fe is carried out. To understand the interaction effects between MoS2 and NO2 in consideration of electronic transport properties has been observed carefully. By bringing dopants and defects into the 2D sheets of MoS2 have significant effects on transport properties which are observed from I-V curves. Finally, we conclude that MoS2 can be used as potential gas sensor and the sensing properties of MoS2 can be enhanced with Fe dopant.

We present our experimental and theoretical study on Co diffusion in the first few atomic layers of Cu(001). While the diffusion of Co atoms in Cu(001) is usually expected to be intense at a temperature $T\ensuremath{\ge}800$ K, in the vicinity of the surface, it is already activated at a considerably lower temperature $T\ensuremath{\sim}650$ K whereas the diffusion in the deep bulk region is still inhibited. This intense near-surface diffusion provides an accumulation of Co atoms in the first six atomic layers upon a single stage Co deposition. The details of the near-surface diffusion are studied by analyzing the distribution of the location depth of the buried single Co atoms. The depth of location of single Co atoms is deduced from scanning tunneling microscopy (STM) data. The subsurface Co atoms induce a perturbation of the electron density of states of the surface which is observable as apparent ringlike ripples in the STM images of the atomically flat Cu surface. The depth of location of the buried Co atoms is determined from the diameter of those rings. The largest amount of Co atoms is found to be in the third layer, emphasizing that the near-surface diffusion should be described by diffusion parameters different from those for bulk diffusion. A model that describes the embedding process of Co atoms into Cu(001) layers is developed. The model assumes Co atoms to diffuse via the vacancy and ring-exchange mechanisms. The energy barriers for the interlayer Co diffusion via those mechanisms are calculated using the nudged elastic band method. The model satisfactorily explains the experimental results. Our study reveals that the energy barriers for Co diffusion in the first five atomic layers of Cu(001) are lower than those in the bulk. This defines the region in which Co diffusion should be considered as a near-surface one.

Angle-resolved photoemission spectroscopy reveals the presence of a two-dimensional electron gas at the surface of In(2)O(3)(111). Quantized subband states arise within a confining potential well associated with surface electron accumulation. Coupled Poisson-Schrödinger calculations suggest that downward band bending for the conduction band must be much bigger than band bending in the valence band. Surface oxygen vacancies acting as doubly ionized shallow donors are shown to provide the free electrons within this accumulation layer. Identification of the origin of electron accumulation in transparent conducting oxides has significant implications in the realization of devices based on these compounds.

Based on the experimental observations, amorphous structural models of graphene oxides (GOs) were constructed and investigated by first-principles computations. Geometric structures, thermodynamic stabilities, and electron density of states of these amorphous GO models were examined and compared with the previously proposed ordered GO structures. The thermodynamically most favorable amorphous GO models always contain some locally ordered structures in the short range, due to a compromise of the formation of hydrogen bonds, the existence of dangling bonds, and the retention of the it bonds. Compared to the ordered counterparts, these amorphous GO structures possess good stability at low oxygen coverage. Varying the oxygen coverage and the ratio of epoxy and hydroxyl groups provides an efficient way to tune the electronic properties of the GO-based materials. (C)2011 Elsevier Ltd. All rights reserved.

In the paper, the values of the thermodynamic critical eld (HC) for francium have been calculated. It has been assumed the wide range of the pressure: p ∈ 〈7.2; 14〉 GPa. The analysis has been performed in the framework of the strong-coupling formalism. It has been predicted that the value of the ratio HC(0)/ √ ρ(0) increases with the increasing pressure from 3.08 meV to 5.84 meV, where ρ(0) denotes the electron density of states at the Fermi level. The dimensionless parameter TCC N (TC) /H 2 C(0) is smaller than in the BCS theory and decreases with pressure from 0.150 to 0.141. The symbol TC represents the critical temperature and C N is the speci c heat for the normal state.

The adsorption of CO and NO molecules on the MgO nanotubes was investigated using density functional theory calculations. The adsorption energies of CO and NO were estimated to ranging from −0.35 to −0.16 eV and −0.28 to −0.13 eV, respectively. The most stable adsorption configurations are those in which the C or N atoms the adsorbates are close to the Mg atom of the tube surface. It was found that the MgO nanotubes selectively act against the CO and NO gaseous molecules. Their electrical conductivity are sensitive to NO gaseous molecule while is not to CO one, indicating that they may be potential sensors for NO molecule. These findings are characterized by analyzing the features in the electron density of states.

Urological cancers comprise approximately one-third of all cancers diagnosed in men worldwide and out of these, prostate cancer is the most common one ( WHO World Cancer Report, 2008 ). Several risk factors such as age, hormone levels, environmental conditions and family history are suspected to play a role in the onset of this disease of otherwise obscure aetiology. It is therefore the medical need that drives multidisciplinary research in this field, carried out by means of various experimental and theoretical techniques. Out of many relevant factors, it is believed that sulphur can take an important part in cancer transformations. We have investigated the prostate cancer cell lines and tissues, along with selected organic and inorganic compounds used as references, by the X-ray absorption fine structure spectroscopy near the sulphur edge energy region. Particularly, the comparison of the experimental results collected during XANES measurements and theoretical calculations of electron density of states with use of the FEFF8 code and LAPW (linearised augmented plane-wave) method has been performed and in this work the first results of our studies are presented.

An atomistic model of substoichiometric germanium oxide is generated through ab initio molecular dynamics. The resulting structure shows a predominance of threefold coordinated Ge and O atoms. We also generate substoichiometric models through bond-switching Monte-Carlo simulations, which preserve the fourfold Ge and the twofold O coordinations. These differing structures are energetically competitive. Alignment of their electron densities of states to that of GeO"2 reveals that the band-gap reduction is similar for both structures, mainly occurring through a shift of the valence band edge.

The classical Monte-Carlo method is used to study the finite-temperature properties of the three-dimensional ( D = 3 ) Falicov–Kimball model in the symmetric case. It is shown that the critical temperature of the phase transition from the low-temperature ordered phase to the high-temperature disordered phase in D = 3 is considerably enhanced in comparison to the two-dimensional case ( D = 2 ). A significant shift to higher values of the Coulomb interaction U (with respect to D = 2 ) is also found for the critical point U c , at which the nature of the phase transition changes from the first to second order. In addition, the temperature dependence of the itinerant electron density of states (DOS) is analysed. For very low-temperatures we have observed a formation of a fine structure inside the principal gap that transforms to a pseudo-gap at higher temperatures and becomes temperature independent for sufficiently large temperatures. In this temperature region we have calculated DOS for different Coulomb interactions and found the Mott-Hubbard transition.

The carrier trapping and emission processes of InAs self-assembled quantum dots (QDs) on GaAs substrates were measured and analyzed using capacitance–voltage techniques and deep-level transient spectroscopy (DLTS). We used different applied biases and filling pulse widths. This allowed the determination of the activation energies of defect/electronic states of the QDs within a range of 0.08–0.59 eV. These values represent the energy levels of the QDs with respect to the host matrix, showing that QDs have band-like interacting energy levels and that DLTS signals are largely affected by the electron density of states of QDs.

The electron density of states for the valence band of ZnSe has been calculated using a self-consistent orthogonalized plane wave (SCOPW) model. In this model the exchange term is approximated by Liberman's energy dependent operator which simulates the Hartree-Fock exchange closely in the atomic case. The model is outlined and the results are compared with values obtained with an energy independent model and experimental results. One concludes that the energy dependent model matches experiment less well than the energy independent model.

The experimental value of H3S a isotope coefficient decreases from 2.37 to 0.31 in the pressure range from 130 GPa to 200 GPa. We have shown that the value of 0.31 is correctly reproduced in the framework of the classical Eliashberg approach in the harmonic approximation. On the other hand, the anomalously large value of the isotope coefficient (2.37) may be associated with the strong renormalization of the normal state by the electron density of states.

The processes of recombination of the photoexcited electron-hole pairs were studied in GaAs/AlGaAs weakly coupled multiple quantum wells, where the photoluminescence emission was composed of the contributions from the Γ−Γ and Γ−X conduction band minibands. Remarkable enhancement of the recombination time was observed when the magnetic field caused depopulation of the higher energy Γ−X miniband. The observed effect is attributed to the magnetic field induced variation of the electron density of states.

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 FeA vacancy (AB-FeA vac model), the AB-terminated with FeB vacancy (AB-FeB vac model), the B-terminated surface (B model), the B-terminated surface with FeB vacancy (B-FeB 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-FeA vac, AB-FeB vac, B and the B-FeB vac models have ferrimagnetic properties, while the B-O vac model has antiferromagnetic property.

Within standard treatments of the interacting electron--phonon system the electron density of states (EDOS) shows no sign of the phonons when the system is in the normal state. On the other hand, emergence of a fine energy scale in the superconducting state makes the phonons readily observable in the EDOS and other spectroscopic quantities. Here we wish to re-examine the conditions under which phonon structure might be present in the normal state. Accounting for a finite, i.e. non-infinite, electronic bandwidth results in easily distinguishable phonon structure in the EDOS. We argue that for narrow band metals, the resolution of photoemission spectroscopy is sufficient for resolving these structures. Manifestations of finite band effects in $K_3C_{60}$ are discussed.

La3Ni2B2N3, which is similar to YNi2B2C and related borocarbides, was earlier studied by the electronic structure calculations [D.J. Singh, W.E. Pickett, Phys. Rev. B 51 (1995) 8668.], and was predicted to be a 3-D metal. In search of new compounds of the borocarbide and related families to get higher TC, we have studied the compound Th3Ni2B2N3, by the first principles full potential electronic structure calculations by the linear augmented plane wave method. We get similar band structure for Th3Ni2B2N3 as found for La3Ni2B2N3, and the various atom-split component density of states show similar properties. The total electron density of states at Fermi level has been increased to about 92 states per Ry per f.u. as compared to 57 states per Ry per f.u. in La3Ni2B2N3. The main increase is due to the increased hybridization of the 5f states as seen by the more prominent low energy tail in the Th-component density of states. Based on this enhancement we predict Th3Ni2B2N3 to be a high temperature superconductor with a Tc in excess of 30 K.

In order to non-destructively evaluate changes in toughness of cast duplex stainless steel, which is frequently used in main coolant pipes of PWR type nuclear power plants, due to thermal aging, we tried to apply thermoelectric power (TEP) measurement. because TEP is sensitive to microstructural material changes, and to clarify the mechanism behind TEP changes due to thermal aging. As a result, TEP of cast duplex stainless steel increased with aging time, and good correlations were found between TEP and toughness. Concerning the mechanism, TEP of high and low Cr content alloys was higher than that of intermediate Cr content alloys. Because high and low Cr areas are created in the ferrite phase due to thermal aging. TEP of the entire material increased. Furthermore, when each Cr fluctuating area acted in parallel, the increase in TEP became larger. According to the Mott-Jones theory, TEP is largely related to the electron density of states at the Fermi level. The electron density of states of Fe–Cr–Ni alloys in the valence band was measured with X-ray photoelectron spectroscopy (XPS). As a result, there was a high correlation between the TEP calculated from the XPS spectrum and the measured TEP. Therefore, we showed experimentally that the electron density of states changed due to variations in Cr concentration, which also affect TEP.

We present low-dimensional functionalization and characterization of electron density of states (DOS) using highly correlated/precisely guided proton beam trajectories and a silicon nanocrystal as a target, representing at a same time a versatile nanolaser technique capable for coherent control of atomic quantum states and for scanning the interior of an atom with resolution comparable to 10% of the Bohr radius., 27 pages, 10 figures, Laser and Particle Beams, Cambridge Journals, 2014

The ionization probability of an atom scattered from an atom adsorbed on a metal surface has been studied theoretically within the time-dependent Anderson-Newns model. The effect of the metal electron density of states, the band filling as well as the relative position of the scattered atom and adsorbed atom energy levels have been considered and the comparison with the results obtained for clean surfaces has been made.