Density functional theory study on the origins of the gap bowing in Zn_1-xMg_xSe

Abstract

Self-consistent density functional theory based on a direct supercell approach is reported for Zn1-xMgxSe pseudobinary alloy. The calculation includes, in a natural way, atomic relaxation and self-consistent charge transfer, hence providing a link between the electronic structure and the interaction energies which decide phase stability. We model the alloys at some selected compositions with ordered structures described in terms of periodically repeated supercells. Results include structural, electronic, and bonding properties as well as the density of occupied states and their variations upon alloying. Using the approach of Zunger and co-workers, the microscopic origins of compositional disorder have been detailed and explained. The disorder parameter (bowing) is found to be small and is mainly caused by the volume deformation effect. The chemical charge transfer also contributes to the bowing parameter at a smaller magnitude, while the relaxation contribution is even smaller.

Fundamental and transport properties of ZnX, CdX and HgX (X = S, Se, Te) compounds

“…3 and 4 respectively, together with the experimental data [45] and previous theoretical work [35]. Further comparisons could also be made with other systems [46][47][48][49][50][51]. We notice a drastic change when the relativistic correction is considered.…”

Structural, electronic, optical and thermodynamic properties of SrxCa1−xO, BaxSr1−xO and BaxCa1−xO alloys

“…The band structure calculations give an indirect band gap -X for CaO and a direct band gap X-X for SrO and BaO. The calculated band gaps for all studied compositions (x = 0, 0.25, 0.50, 0.75, 1) are given in Table 3, along with the available experimental and theoretical results [11,12,[36][37][38][39][40] for comparison. In view of Table 3, it is clear that our calculated values for the band gaps for CaO, SrO and BaO, using the PP-PW method within the GGA, are underestimated compared to the measured ones.…”

“…To analyze the physical origins of the band gap bowing b g , we follow the procedure of Bernard and Zunger [37][38][39] and decompose the bowing parameter b g into three physically distinct contributions. By considering the fact that the bowing dependence on the composition is marginal, they limited their calculations at x = 0.5.…”

First-Principles Study of Cubic BxIn1-xN Ternary Alloys

“…These include methods based on the dielectric two-band model [6], semi-empirical tight-binding method [7,8] semi-empirical pseudo-potential method [9,10], ab initio pseudo-potential method [11][12][13][14][15][16][17][18][19][20][21][22] and full potential linearized augmented plane wave (FP-LAPW) method [23,24]. To our knowledge, there is no theoretical investigation of B x In 1−x N alloy.…”