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The prospect of α-Ga2O3 in optical and electrical devices application is fascinating. In order to obtain better performance, Ge and F elements with similar electronegativity and atomic size are selected as dopants. Based on density functional theory (DFT), we systematically research the electronic structure and optical properties of doped α-Ga2O3 by GGA+U calculation method. The results show that Ge atoms and F atoms are effective n-type dopants. For Ge-doped α-Ga2O3, it is probably obtained under O-poor conditions. However, for F-doped α-Ga2O3, it is probably obtained under O-rich conditions. The doping system of F element is more stable due to the lower formation energy. In this investigation, it is found that two kinds of doping can reduce the α-Ga2O3 band gap and improve the conductivity. What is more, it is observed that the absorption edge after doping has a blue shift and causes certain absorption effect on the visible region. Through the whole scale of comparison, Ge doping is more suitable for the application of transmittance materials, yet F doping is more appropriate for the application of deep ultraviolet devices. We expect that our research can provide guidance and reference for preparation of α-Ga2O3 thin films and photoelectric devices.

We investigate magnetic ordering and electronic structures of Cr2MoO6 under hydrostatic pressure. To overcome the band gap problem, the modified Becke and Johnson exchange potential is used to investigate the electronic structures of Cr2MoO6. The insulating nature at the experimental crystal structure is produced, with a band gap of 1.04 eV, and the magnetic moment of the Cr atom is 2.50 μ B, compared to an experimental value of about 2.47 μ B. The calculated results show that an antiferromagnetic inter-bilayer coupling–ferromagnetic intra-bilayer coupling to a ferromagnetic inter-bilayer coupling–antiferromagnetic intra-bilayer coupling phase transition is produced with the pressure increasing. The magnetic phase transition is simultaneously accompanied by a semiconductor–metal phase transition. The magnetic phase transition can be explained by the Mo–O hybridization strength, and ferromagnetic coupling between two Cr atoms can be understood by empty Mo-d bands perturbing the nearest O-p orbital.

The electronic structures, optical dielectric functions, elastic properties, and lattice dynamics of Ba2ZnWO6 have been investigated by using the generalized gradient approximation. The density of states and distributions of charge density show that O and Ba tend toward ionic bond, but O and W or Zn display the covalent bond character. The calculated energy band structure shows that Ba2ZnWO6 is a wide indirect band gap semiconductor. The static value 2.28 of the refractive index is attained. The analysis of the elastic properties of Ba2ZnWO6 indicates a rather weak elastic anisotropy. The phonon dispersion is calculated, suggesting no structural instability, which is agreement with the recent low temperature neutron diffraction experiments. The mensurability Cv (phonon heat capacity) as the function of the temperature is also calculated to judge our results for future experiment.

We use a modified Becke—Johnson exchange plus a local density approximation correlation potential within the density functional theory to investigate the electronic structures of Hg1−xCdxTe and In1−xGaxAs with x being 0, 0.25, 0.5, 0.75, and 1. For both of the two series, our calculated energy gaps and dielectric functions (real part 1 and imaginary part 2) are in agreement with the corresponding experimental results with x being between 0 and 1. The calculated zero-frequency refractive index varies greatly with x for Hg1−xCdxTe, but changes little with x for In1−xGaxAs, which is consistent with the real parts of their dielectric functions. Therefore, this new approach is satisfactory to describe the electronic structures and the optical properties of the semiconductors.