Specific features of electronic structures and optical susceptibilities of g-BC₃ and t-BC₃ phases

Abstract

Details of comparison for some specific features of electronic structures and optical susceptibilities of g-BC3 and t-BC3 phases are provided. Calculations show that the g-BC3 phase is a narrow band gap semiconductor constructed from the ABAB stacking sequence. Whereas t-BC3 is a metallic phase constructed by a sandwich-like metal-insulator lattice from an alternately stacking sequence of metallic CBC and insulating CCC blocks. The two phases possess only two types of bonds (B-C and C-C). The density of states at the Fermi level N(EF) of the t-BC3 phase is determined by the overlapping of B-2p and C-2p empty orbitals of the CBC block with C-2p empty orbitals of the CCC block, and the shape of the Fermi surface originated from these empty orbitals. The B atoms cause a small perturbation on the C-ring's structure and hence to the charge density distribution. The linear optical properties of the two phases confirm the existence of the lossless regions and the considerable anisotropy. The second harmonic generation of the t-BC3 phase shows that χ(ω) is the dominant component of about 3.9 pm V(-1) at the static limit and 5.8 pm V(-1) at λ = 1064 nm, which suggests that the t-BC3 phase could be considered as a promising nonlinear optical material in comparison with the well known KTiOPO4 nonlinear optical single crystal.

Predicting the electronic structure, magnetism, and transport properties of new Co-based Heusler alloys

“…From the last few decades, the Heusler materials have been an important topic for their potential usage in novel spin‐based devices, thermoelectrics, spin filters, data storage devices, and so on. To achieve this, density functional theory (DFT) has proven to be a handy tool for the researchers worldwide …”

“…To achieve this, density functional theory (DFT) has proven to be a handy tool for the researchers worldwide. [4][5][6][7] Heusler alloys have long been in demand for their interesting physical properties like half-metallicity, 8 high spin polarization at Fermi level, 9 ferromagnetism and large curie temperatures, 10 thermoelectric performance, 11 etc. With such spell-bound properties, they have emerged as a new class of smart materials.…”

Transport properties of g-BC3and t-BC3phases

“…Therefore, due to a lack information regarding the thermoelectric properties of the superhard metallic g-BC 3 and t-BC 3 compounds, and as natural extended to our recent work on g-BC 3 and t-BC 3 (ref. 29) we have addressed ourselves for comprehensive theoretical calculations based on the density functional theory (DFT) within all-electron full potential method and the semi-classical Boltzmann theory as incorporated in BoltzTraP code 30 to calculate the thermoelectric properties of g-BC 3 and t-BC 3 phases. In this calculation we have employed the all-electron full potential linear augmented plane wave plus local orbitals (FPLAPW + lo) method.…”

“XA6” octahedra influencing the arrangement of anionic groups and optical properties in inverse-perovskite [B6O10]XA3(X = Cl, Br; A = alkali metal)

“…As a-RBOC belongs to the 3m point group, there are three independent elements: d 22 , d 31 and d 33 owing to Kleinman symmetry. 36 Because the first-principles methods have succeeded in estimating NLO coefficients of many crystals, [37][38][39][40][41][42] the tensors d 22 , d 31 and d 33 were calculated via the reduced length-gauge formalism. 30 The calculated results are, d 22 = 0.86 pm V À1 , d 31 = 0.10 pm V À1 , and d 33 = 0.57 pm V À1 .…”