Electronic structure of the TbMn<Subscript>0.33</Subscript>Ge<Subscript>2</Subscript> compound: Band calculation and optical experiment

The results of the investigation of the electronic structure and optical properties of the TbMn_0.33Ge₂ compound have been presented. The spin-polarized calculations of the band spectrum have been performed within the framework of the local spin density approximation (LSDA) with a correction for strong correlations in the 4f shell of the rare-earth ion (the LSDA + U method). The optical constants have been measured using the ellipsometric method and a number of spectral and electronic characteristics of the compound under investigation have been determined over a wide range of wavelengths. The interband part of the experimental dependence of the optical conductivity has been interpreted using the results of the calculation of the electron density of states.     

Effect of copper and cobalt impurities on the electronic structure and optical spectra of the intermetallic compound PrNi5

The electronic structure and optical properties of the intermetallic compound PrNi₅ and their evolution during the substitution of copper or cobalt atoms for nickel atoms have been investigated. The band spectra of the studied compounds have been calculated in the local spin density approximation corrected to account for strong electron-electron interactions in the 4f shell of the rare-earth ion (LSDA + U method). The dispersion relations of the optical conductivity in the interband light absorption region have been interpreted using the results of calculations of the electron density of states.     

Specific features of the electronic structure and spectral properties of NdNi5 − x Cu x compounds

The spectral properties of the intermetallic compounds NdNi_{5 ? x} Cu _x (x = 0, 1, 2) have been studied using optical ellipsometry in the wavelength range 0.22–16 μm. It has been established that substitution of copper atoms for nickel leads to noticeable changes in the optical absorption spectra, plasma frequencies, and relaxation frequencies of conduction electrons. Spin-polarized calculations of the electronic structure of these compounds have been performed in the local spin density approximation allowing for strong electron correlations (LSDA + U method) in the 4f shell of the rare-earth ion. The calculated electron densities of states have been used to interpret the experimental dispersion curves of optical conductivity in the interband light absorption region.     

Photodesorption of rubidium atoms from a sapphire surface

The optical properties of the GdRhGe compound have been investigated in a wide spectral range by ellipsometry. Self-consistent calculations of the electronic structure have been performed within the local electron spin density approximation with a correction to strong electron interactions in the 4f shell of gadolinium ions (LSDA+U method). The experimental dispersion relation of the optical conductivity in the region of interband light absorption is interpreted based on the results of calculating the electron densities of states.     

The Influence of Copper Impurity on the Electronic Structure and Optical Properties of TmNi<Subscript>5</Subscript> Compound

Investigations of the electronic structure and optical properties of TmNi_5–хСu_x (х = 0, 1, 2, 3) compounds were performed. Self-consistent calculations of the band spectrum have been performed in the local electron-spin-density approximation with a correction on strong electron interactions within the LSDA + U method. Total and partial densities of electron states associated with thulium, nickel, and copper atoms have been calculated. Optical conductivity, the behavior of which is interpreted for each compound taking into account the performed calculations, has been measured by the ellipsometry method in a wide wavelength range of 0.22–16 μm. Concentration dependences of plasma and relaxation frequencies of conduction electrons have been determined.     

Role of Fe and Co in optical conductivity and electronic structure of TbNi4Fe and TbNi4Co

Optical properties of two intermetallic compounds TbNi₄Fe and TbNi₄Co have been studied employing ellipsometry in a spectral range 0.22–15 μm to reveal their characteristic features in comparison with the parent compound TbNi₅. The electronic structure of TbNi₄Fe and TbNi₄Co was calculated within the LSDA + U method (local spin density approximation with Hubbard U-correction). Based on the calculated electronic structure results, the theoretical optical conductivity was calculated and used to interpret experimental conductivity in the range of interband optical absorption.     

First-principles linear muffin-tin orbital investigations in the electronic and magnetic structures of double perovskites Ba2TMoO6 (T=V,Cr, Mn,Fe and Co)

The electronic and magnetic structures of ordered double perovskites Ba₂TMoO₆ (T=V, Cr, Mn, Fe and Co) are systematically investigated by means of the first-principle linear muffin-tin orbitals with the atomic-sphere approximation (LMTO-ASA) method. The calculations are performed by using the both local spin density approximation (LSDA) and the LSDA+U Coulomb interaction schemes. The results show a half-metallic ferrimagnetic ground states for T=Cr, Fe and Co in LSDA+U treatment, whereas half-metallic ferromagnetic character is observed for T=V. For T=Mn, insulating ground state is obtained, stabilized in the antiferromagnetic state. The LSDA+U calculations yield better agreement with the theoretical and the experimental results than do the LSDA.     

Specific features of the electronic structure and spectral characteristics of the Gd<Subscript>5</Subscript>Si<Subscript>3</Subscript> compound

The electronic structure and optical properties of the hexagonal intermetallic compound Gd₅Si₃ are investigated. The spin-polarization calculation of the band spectrum is performed in the local spin density approximation, taking account for the strong electron correlations in the 4 f shell of a Gd ion (LSDA + U method). Optical constants of the compound in the wavelength range of 0.22–15 μm are determined by the ellipsometry technique and some spectral characteristics are calculated. The frequency dependence of optical conductivity in the light quantum absorption region is analyzed on the basis of the calculated electron density of states.     

Electronic structure and optical properties of the HoCoSi and ErNiSi compounds

The electronic structure and the optical properties of the HoCoSi and ErNiSi compounds are studied. Spin-polarized band calculations are performed in the local electron density approximation corrected for the strong electron–electron interactions in the 4f shell of a rare-earth ion (LSDA + U method [11]). The optical constants are measured by ellipsometry in a wide wavelength range, and the frequency dependences of a number of spectral parameters are determined. The calculated densities of states are used to interpret the structural features of the interband optical conductivities of the intermetallic compounds.     

First-principles study of electronic structure and magnetism of cubic Al1−xErxN using the LSDA+U approach

First-principles calculations, by means of the full-potential augmented plane wave method using the LSDA+U approach (local spin density approximation with Hubbard-U corrections), have been carried out for the electronic structure of the Al_0.75Er_0.25N. The LSDA+U method is applied to the rare-earth 4? states. We have investigated the electronic and magnetic properties.The Al_0.75Er_0.25N is shown to be a semiconductor, where the filled ? states are located in the valence bands and the empty ones above the conduction band edge. The magnetic interaction of the rare-earth ion with the host states at the valence and conduction band edges has been investigated and discussed.     

Electronic and Spectral Properties of RRhSn (R = Gd,Tb) Intermetallic Compounds

The investigations of electronic structure and optical properties of GdRhSn and TbRhSn were carried out. The calculations of band spectrum, taking into account the spin polarization, were performed in a local electron density approximation with a correction for strong correlation effects in 4f shell of rare earth metal (LSDA + U method). The optical studies were done by ellipsometry in a wide range of wavelengths, and the set of spectral and electronic characteristics was determined. It was shown that optical absorption in a region of interband transitions has a satisfactory explanation within a scope of calculations of density of electronic states carried out.     

FP-LMTO calculations of elastic and electronic properties of the filled skutterudite CeRu4P12

First-principles calculations have been used to investigate the structural, electronic and elastic properties of the filled skutterudite CeRu₄P₁₂, using the full-potential linear muffin-tin orbital (FP-LMTO) method. The exchange-correlation energy is described in the local spin density approximation (LSDA) using the Perdew–Wang parameterization. The results of the electronic properties show that this compound is an indirect band gap material. A special interest has been made to the determination of the elastic constants since there have been no available experimental and theoretical data. The energy band gaps and their volume and pressure dependence are investigated. Our results of the ground-state electronic properties are found to agree with experimental results.     

Magnetic properties,electronic structure,and optical properties of the filled skutterudite BaFe4Sb12

The magnetic properties, electronic structure, and optical properties of the filled skutterudite BaFe₄Sb₁₂ are calculated by the first-principles full-potential linearized augmented plane wave (FPLAPW) plus local orbital method. It is found that the local spin density approximation (LSDA) method appears more accurate than the generalized gradient approximation (GGA) method in calculating the electronic structures and optical properties of this compound. Furthermore, our calculated lattice constant and spin magnetic moments with the LSDA method are in overall better agreement with experiment. In contrast with recent experiment, our calculations are in good agreement with experimental reflectivity spectra and optical conductivity spectrum.     

Ab initio study of the structural,electronic, elastic and magnetic properties of Cu2GdIn,Ag2GdIn and Au2GdIn

We preformed first-principle calculations for the structural, electronic, elastic and magnetic properties of Cu₂GdIn, Ag₂GdIn and Au₂GdIn using the full-potential linearized augmented plane wave (FP-LAPW) scheme within the generalized gradient approximation by Wu and Cohen (GGA-WC), GGA+U, the local spin density approximation (LSDA) and LSDA+U. The lattice parameters, the bulk modulus and its pressure derivative and the elastic constants were determined. Also, we present the band structures and the densities of states. The electronic structures of the ferromagnetic configuration for Heusler compounds (X₂GdIn) have a metallic character. The magnetic moments were mostly contributed by the rare-earth Gd 4f ion.     

First-principles study of the structural properties and magnetism of NpNiSn

First-principles calculations based on density functional theory have been performed on the intermetallic compound NpNiSn. The electronic density of states, bonding properties and equilibrium volume have been studied using relativistic full-potential APW+lo calculations. The magnetocrystalline anisotropy energy has been estimated from total-energy calculations and the a-axis is predicted to be the easy axis of magnetization. The LSDA+U method has been employed to mimic the orbital polarization and to obtain the total magnetic moments.     

A full potential all-electron calculation on electronic structure of NiO

We perform a first principle calculation on NiO system, a prototypical correlated electronic system due to partial filled 3d electronic shell, using various density functional theory (DFT) and hybrid functional methods inclusion of spin polarization (SP), on-site Coulomb repulsion U and spin–orbit coupling (SOC) effects. It is shown that localized spin density approximation (LSDA) plus U (LSDA?+?U) correctly reproduce experimental lattice parameter, while spin polarization generalized gradient approximation (SP?+?GGA?+?U) obviously overestimates lattice parameter. LSDA?+?U/SP?+?GGA?+?U band gaps and magnetic moments are in agreement with experimental data, and correctly predict NiO to be an insulator. NiO undergoes a Mott–Hubbard metal–insulator transition (MIT) by addition of Coulomb interaction U. Our LSDA?+?SOC calculation shows that SOC further splitting of Ni d e_g and t_2g orbitals into d_z2, d_xy, d_x2y2 and d_xz?+?d_yz orbitals, and SP nearly cancels out SOC effect, giving rise to symmetry of density of states (DOS) for spin-up and spin-down states, hence appearance of zero net magnetic moment. For LSDA?+?U?+?SOC calculation, combination effect of SP, U and SOC results in non-occupying of spin-up conduction band and a negligible density of states for spin-down states.     

Influence of aluminum impurity on the electronic structure and optical properties of the TbNi5 intermetallic compound

The electronic structure of the TbNi_{5 ? x} Al _x intermetallic compounds (x = 0, 1, 2) is calculated in the local electron density approximation with the correction to strong electron correlations in 4f shell of terbium ions. Spectral properties of these compounds are measured by ellipsometry in a wavelength range of 0.22–16 μm. Frequency dependences of optical conductivity in the region of interband optical absorption are interpreted based on the results of calculations of electron densities of states. The relaxation and plasma frequencies of conduction electrons are determined.     

Ab initio studies of half-metallic ferromagnetism in carbon-doped CeO2

The electronic structures and magnetic properties in Carbon-doped CeO₂ have been investigated by means of first-principles calculations based on the LSDA+U scheme. The results demonstrate a magnetic moment of 2.00 μ_B per supercell with one Carbon dopant which mainly stems from Hund’s rule coupling based on rather localized 2p, 5d and 4f states. The hole-mediated long-range magnetic coupling between local magnetic moments can be attributed to the collective effects of the p–p, p–d, and p–f hybridizations between C and neighboring O or Ce atoms. Ferromagnetism and half-metallic characteristics of C-doped CeO₂ make it possible to be an ideal material for spintronic devices.     

Ab initio simulation of the electron structure and optical spectroscopy of ErRhGe compound

The results of investigation of the electronic structure and optical properties of ErRhGe are presented. The band spectrum of this compound is calculated in the local electron spin density approximation with correction for strong electron interactions in the 4f shell of the rare-earth metal (LSDA + U method) with allowance for the spin polarization. The optical constants of the compound are measured, and a number of spectral and electronic characteristics are determined by the ellipsometric method in a wide range of wave-lengths. Structural features of the optical conductivity spectrum in the interband absorption region are interpreted on the basis of the calculated electron state density.