Electronic structure of MgB2

Results of ab initio electronic structure calculations on the compound MgB₂ using the FPLAPW method employing GGA for the exchange-correlation energy are presented. Total energy minimization enables us to estimate the equilibrium volume, c/a ratio and the bulk modulus, all of which are in excellent agreement with experiment. We obtain the mass enhancement parameter by using our calculated D (E _F) and the experimental specific heat data. The T _c is found to be 24.7 K.     

Electronic structure of the CuBS2 crystal

The band structure and spectra of the total and projected densities of states of a new crystal of the chalcopyrite family, namely, CuBS₂, have been calculated in terms of the density functional theory. It has been found that the crystal is a pseudo-direct-band-gap semiconductor, and the best theoretical estimate of the optical band gap is 3.44 eV. The upper valence band of the CuBS₂ crystal basically consists of the contributions from the p states of S atoms and the d states of Cu atoms. The crystal splitting is 0.2 eV. The bottom of the conduction band is basically formed by the sp states of boron and sulfur atoms with an admixture of the s states of copper atoms.     

Electronic structure of La2CuO4

The electronic band structure of La₂CuO₄ is performed using self-consistent linear muffin-tin orbital method. The 17 band complex is found to arise mainly from the overlap between Cu-3d and O-2p wavefunctions. The calculated density of states at the Fermi energy (N E _F), the conduction band-width and the electronic specific heat coefficient are given.     

Electronic structure of CaSi and CaSi2

The electronic properties of calcium silicides (CaSi and CaSi₂) are investigated through a joint experimental and theoretical study using Bremsstrahlung Isochromat spectroscopy (BIS) and self-consistent calculation of the electronic states by the Linear Muffin-Tin Orbitals (LMTO) method in the Atomic Sphere Approximation (ASA). The peculiar crystal structure of CaSi₂ with two inequivalent Si atoms is responsible for a well defined BIS feature. We found that the calculated high energy DOS features are consistently lower in energy compared to the BIS spectra. Inclusion of the cross-sections of different states into the calculations improves the agreement between the experimental spectra and the calculated curve. We also show that considerable covalent character is present in the bond of calcium silicides.     

Electronic structure of Sr2FeMoO6

We have analyzed the unusual electronic structure of Sr2FeMoO6 combining ab initio and model Hamiltonian approaches. Our results indicate that there are strong enhancements of the intra-atomic exchange strength at the Mo site as well as the antiferromagnetic coupling strength between Fe and Mo sites. We discuss the possibility of a negative effective Coulomb correlation strength ( U(eff)) at the Mo site due to these renormalized interaction strengths.     

2H-PbI2晶体的电子结构和力学性质

采用基于密度泛函平面波赝势方法(PWP)方法,计算了六角晶系2H-PbI2晶体的电子结构、力学性质和硬度。采用局域密度近似(LDA)方法计算的晶格常数、带隙、弹性常数与实验值和理论值符合较好。计算表明,2H-PbI2是一种直接带隙的半导体,带隙大约为2。38eV。运用复杂晶体硬度计算公式计算了六角晶系2H-PbI2晶体的硬度,硬度值大约为2. 54 GPa。还发现2H-PbI2晶体的各向异性非常明显。     

Electronic structure of Fe2CrSn

From the first principles calculation based on the density functional theory, we find that consideration of electron–electron correlation drives Fe₂CrSn from a barely half-metallic state to a magnetic semiconductor. However, in both cases, the magnetic state remains ferrimagnetic with a total spin moment of 2μ_B$2{\mathrm{\mu }}_{\mathrm{B}}$, with Cr carrying a large local moment that is oppositely aligned to that of Fe.     

Electronic structure of the H+2 molecule

Main results of investigations aimed at a construction of the classical model of the H⁺₂ molecule are presented. The form of the orbit of the electron, binding two nuclei of the H⁺₂ molecule together has been deciphered. Theoretical value of the structural parameter, which is the distance between nuclei times the binding energy of the electron, was found to be equal with a high accuracy to that experimentally measured.     

Electronic structure and instability of Ni2MnGa

The nature of the magnetic and structural phase transitions in the Heusler alloy Ni₂MnGa is studied by numerical calculations of the electronic structure, generalized susceptibility, and various Fermi-surface cross sections. Fiz. Tverd. Tela (St. Petersburg) 41, 684–690 (April 1999)     

Electronic structure of ErH2

A band structure study reveals that in contrast to the pure rare earth metal, the Fermi level of the dihydride falls near the bottom of the 5d band, in a region of low density of states; consequences on Fermi surface geometry, magnetic properties and resistivity are suggested. Below the metal d states lie two overlapping metal-hydrogen bands, in agreement with Weaver's photoemission data and Switendick's result on YH₂.