Abstract In this study, we have investigated the structural, electronic, and elastic properties of a new series of Os2YAl, (Y=Sc, Ti, V) alloys called “Full Heusler”, based on the Wien2k code using the functional density theory (DFT). The exchange and correlation energy are evaluated as part of the LDA approximation. The results showed that Os2VAl was more stable and harder than Os2ScAl, and Os2TiAl. The electronic band structures and density of states (DOS) of the compounds indicate that they are metallic because there is no bandgap in these three materials these results have been shown by three approaches (LDA, TB-mBJ, and SOC). Near the Fermi level, the energy is mainly occupied by the Os-5d and Sc, Ti, V-3d electrons. According to the results of the second-order elastic constants, these compounds met Born’s criteria for mechanical stability. The elastic properties indicate that our compounds are ductile, anisotropic, and rigid. All the calculations and the data were compared with the results obtained with different methods in terms of its mechanical and electronic behavior, Os 2 VAl was found to have better physical properties than Os2ScAl, and Os2TiAl.

Abstract Using ab-initio calculations, we studied the structural, elastic, and electronic properties of Sc2SiX compounds with, (X=C, N). The negative formation energy and the positive cohesive energy indicate that these compounds are energetically stable and can be synthesized in normal conditions. Sc2SiC and Sc2SiN compounds are mechanically stable, estimated by the individual elastic constants. Elastic constants and modulus increase when C is substituted by N. The elastic anisotropy in Sc2SiC is high compared to Sc2SiN. Both nanolaminates are fragile in nature. Sc2SiC is more conductive than Sc2SiN. The calculated electron band structures and the density of states imply that the chemical bond in two compounds is a combination of covalent, ionic, and metallic nature. The main factors governing the electronic properties are the hybrid states Sc- 3d, Si-3p, and C -2p and the bond (p-d) stabilizes the structure. Fermi’s surface characteristics have been studied for the first time, which are changed when replacing N by C. Based on the estimate of the total energy, we conclude that the replacement of C by N will lead to a stabilization of the hexagonal structure and a decrease of the metallic support.

Abstract In this study, we have employed the first-principle methods based on density functional theory to investigate the structural, electronic, and optical properties of Al0.50Ga0.50NxSb1-x in zincblende structure. The exchange and correlation potential is described by the generalized gradient approximation of Perdew, Burke, and Ernzerhof (GGA-PBEsol) coupled with TB-mBJ approaches. The studied structures show that all structures are semiconductors and have a direct bandgap except Al0.50Ga0.50N0.25Sb0.75, which has a semi-metallic behavior. The optical properties such as refractive index, extinction coefficient, and optical conductivity are discussed in detail. Our result shows these materials are considered as promising materials for optoelectronic applications in the visible and infrared region. To our knowledge, this is the first time that a study has been done on this alloy, and we would like it to serve as a reference for the next studies.

Abstract In this study, we have employed the first-principle methods based on density functional theory to investigate the structural, elastic, electronic, and magnetic properties of BBi0.75Mn0.125N0.125. The exchange and correlation potential are described by the generalized gradient approximation of Perdew, Burke, and Ernzerhof (GGA-PBEsol) + SOC coupled with TB-mBJ approaches. The studied structure shows that the compound BBi0.75Mn0.125N0.125 is stable in the ferromagnetic phase, the elastic property indicates that the structure is brittle and mechanically stable. The half-metallic description is predicted with the energy spin bandgap in the spin-up channel. The structure attributed to half-metallic ferromagnetism could be suitable for spintronics devices. To our knowledge, this is the first time that a study has been done on this alloy, and we would like it to serve as a reference for the next studies.

Abstract In this study, we have investigated the structural, electronic, and magnetic properties of the Rb2NaVF6 compound. We have performed our calculations by the use of first-principle methods based on spin-polarized density functional theory, where the electronic exchangecorrelation potential is treated by the generalized gradient approximation GGA- PBEsol coupled with the improved TB-mBJ approach. The calculated structural parameters of Rb2NaVF6 are in good agreement with the available experimental data. Rb2NaVF6 exhibits a halfmetallic ferromagnetic feature with a spin polarization of 100% at the Fermi level and a direct large half-metallic gap of 3.582 eV. The total magnetic moments are 2 µB. This material is half-metallic ferromagnets, and it can be potential candidates for spintronics applications at a higher temperature.

Resumo: Exceto em alguns casos especiais, os métodos de cálculo de volume utilizam grids, curvas de nível e volume, por meio de TIN (Triangulated Irregular Network). Neste estudo, para avaliar a precisão destes métodos, um sistema de grid foi estabelecido em uma área e o volume foi calculado utilizando as três formas citadas. Concluiu-se que o método das curvas não obteve resultados tão bons quanto os demais. Assim, propõe-se uma fórmula precisa para cálculo de volume utilizando as curvas.

Abstract: Except some special cases, commonly used volume computation methods are grids method, contours method and volume computations by utilizing TIN (Triangulated Irregular Network). In this study, to investigate the precisions of these techniques, a grid system is established in an undulating area and volume of the mound is determined by using these three volume computation methods. It is found out that contour method results were not as price as the other two methods. Thus, a precise formula for volume computations using contours method is proposed.

As técnicas RTK (Real Time Kinematic) e RTK em rede normalmente usadas, ou seja, MAX, I-MAX, FKP e VRS, foram testadas por medidas mensais realizadas durante um ano na Florida. Adicionalmente, foram usadas as mensagens RTCM versões 2 e 3 juntamente com as medidas I-MAX e VRS. Os resultados apontaram que grande parte das coordenadas horizontais variou alguns centímetros e as mudanças nas coordenadas verticais são menores do que dois decímetros. Em termos de coordenadas horizontais os melhores resultados foram alcançados com o método I-MAX3 e o FKP produziu os piores resultados. Em termos de coordenadas verticais quase todos os resultados são parecidos; entretanto, os melhores resultados foram alcançados com o método VRS3. Aparentemente I-MAX3 tem melhores resultados do que I-MAX2 a que VRS3 apresenta melhores resultados do que VRS2. Além disso, MAX não se destacou entre as outras técnicas

Commonly used real time kinematic (RTK) network (RTK Network) techniques, i.e., MAX, I-MAX, FKP and VRS, are tested by taking monthly measurements for a year in Florida. Additionally, RTCM message versions 2 and 3 are used with I-MAX and VRS measurements. The results revealed that mostly, horizontal coordinates vary a few centimeters and generally changes in vertical coordinates are less than two decimeters. In terms of horizontal coordinates, the best results are produced by I-MAX3 method and FKP yielded the worst results. In terms of vertical coordinates, almost all results look alike; however, the best results are produced by VRS3 method. It appears that I-MAX3 performed better than I-MAX2 and VRS3 performed better than VRS2. Yet, MAX did not stand out among other techniques.