Non-local exchange correlation functionals impact on the structural, electronic and optical properties of III–V arsenides

Abstract

Exchange correlation (XC) energy functionals play a vital role in the efficiency of density functional theory (DFT) calculations, more soundly in the calculation of fundamental electronic energy bandgap. In the present DFT study of III-arsenides, we investigate the implications of XC-energy functional and corresponding potential on the structural, electronic and optical properties of XAs (X = B, Al, Ga, In). Firstly we report and discuss the optimized structural lattice parameters and the band gap calculations performed within different non-local XC functionals as implemented in the DFT-packages: WIEN2k, CASTEP and SIESTA. These packages are representative of the available code in ab initio studies. We employed the LDA, GGA-PBE, GGA-WC and mBJ-LDA using WIEN2k. In CASTEP, we employed the hybrid functional, sX-LDA. Furthermore LDA, GGA-PBE and meta-GGA were employed using SIESTA code. Our results point to GGA-WC as a more appropriate approximation for the calculations of structural parameters. However our electronic bandstructure calculations at the level of mBJ-LDA potential show considerable improvements over the other XC functionals, even the sX-LDA hybrid functional. We report also the optical properties within mBJ potential, which show a nice agreement with the experimental measurements in addition to other theoretical results.

Modified Becke–Johnson (mBJ) exchange potential investigations of the optoelectronic structure of the quaternary diamond-like semiconductors Li2CdGeS4 and Li2CdSnS4

“…It is clear that for these two crystals the highest and the lowest energy level bands are positioned at Γ, which exhibit direct band gaps of 2.461 and 3.16 eV for Li 2 CdGeS 4 and Li 2 CdSnS 4 compounds respectively. The computed band gaps are smaller than the experimental values (3.10 for Li 2 CdGeS 4 and 3.26 for Li 2 CdSnS 4 ), but giving close agreement to the experimental measurements of diffuse-reflectance spectroscopy [1] compared to the previous theoretical work of Li et al [11]. Furthermore, in the present investigations, the band gap nature of Li 2 CdGeS 4 is found direct compared to Li et al [11], where it was found indirect.…”

“…The modified Becke-Johnson (mBJ) [10,11] potential is used for the exchange and correlation effects. The Li 2 CdGeS 4 and Li 2 CdSnS 4 compounds have an orthorhombic symmetry.…”

“…We emphasized on the changes of band gaps and optical properties due to the incorporation of substituting Ge or Sn. Compared to former theoretical work based on pseudopotential approach and performed by Li et al [9], here we employ the most recent and accurate approach (mBJ) [10,11] to determine the band gap and their nature (direct or indirect). The outline of this paper is as follow: in the next section, we give brief details about the computational.…”

Calculated electronic, transport, and related properties of zinc blende boron arsenide (zb-BAs)

“…The LDA calculation of Anua and his group 13 17 reported the band gap values of 1.1 and 1.60 eV for their LDA and GW calculations, respectively. A first principle, self-consistent, orthogonalized-plane wave calculation (SCOPW) of Skutel 9 yielded an indirect band gap of 1.6 eV from U to X.…”

Сложная структура оптических переходов с остовных d-уровней кристаллов InAs и InSb

“…При этом в теоретических ра-ботах [2,[18][19][20][21][22] по d-зонам основное внимание уделе-но не природе этих структур, а проблеме завышения положения среднего уровня d-зон на ∼ 3−4 эВ в при-ближении локальной плотности (LDA) и обобщенного градиентного приближения (GGA). Попытка теорети-ческого описания оптических свойств кристалла InAs без учета экситонных эффектов в области энергий > 10 эВ представлена в работе [23]. В области энергий 10−17 эВ теоретические спектры отражения в [23] в 2−3 раза интенсивнее экспериментальных [13] и со-держат множество (∼ 6−7) очень слабых максимумов и ступенек.…”