Electronic and optical properties of thiogermanate AgGaGeS: theory and experiment.

The electronic and optical properties of an AgGaGeS crystal were studied by first-principles calculations, where the full-potential augmented plane-wave plus local orbital (APW+lo) method was used together with exchange-correlation pseudopotential described by PBE, PBE+, and TB-mBJ+ approaches. To verify the correctness of the present theoretical calculations, we have measured for the AgGaGeS crystal the XPS valence-band spectrum and the X-ray emission bands representing the energy distribution of the electronic states with the biggest contributions in the valence-band region and compared them on a general energy scale with the theoretical results. Such a comparison indicates that, the calculations within the TB-mBJ+ approach reproduce the electron-band structure peculiarities (density of states - DOS) of the AgGaGeS crystal which are in fairly good agreement with the experimental data based on measurements of XPS and appropriate X-ray emission spectra.

First-principles study on the structural properties of 2D MXene SnSiGeN and its electronic properties under the effects of strain and an external electric field.

The MXene SnSiGeN monolayer as a new member of the MoSiN family was proposed for the first time, and its structural and electronic properties were explored by applying first-principles calculations with both PBE and hybrid HSE06 approaches. The layered hexagonal honeycomb structure of SnSiGeN was determined to be stable under dynamical effects or at room temperature of 300 K, with a rather high cohesive energy of 7.0 eV.

Layered post-transition-metal dichalcogenide SnGeN as a promising photoelectric material: a DFT study.

First-principles calculations were performed to study a novel layered SnGeN compound, which was found to be dynamically and thermally stable in the 2H phase, with the space group 6̄2 and lattice constant = 3.143 Å. Due to its hexagonal structure, SnGeN exhibits isotropic mechanical properties on the x-y plane, where the Young's modulus is 335.