研究目的
Investigating the electronic and optical properties of antimony sulphide (Sb2S3) nanowire using first-principles calculations to understand changes from bulk to nanowire structure.
研究成果
The Sb2S3 nanowire exhibits an indirect band gap of 0.12 eV, significantly lower than the bulk value, due to quantum confinement effects. The density of states is higher in the nanowire, with changes in orbital contributions. Optical properties show increased absorption coefficient and reflectivity in the visible range, making it promising for solar cell applications. However, the underestimated band gap highlights the need for more advanced computational methods in future studies.
研究不足
The DFT calculations using EV-GGA underestimate the band gap compared to experimental values. The study is limited to computational methods and does not include experimental validation. The supercell method may not fully capture all quantum effects, and more accurate but expensive methods like GW approximation could improve results.
1：Experimental Design and Method Selection:
The study uses density functional theory (DFT) with the full-potential linearized augmented plane wave (FP-LAPW) method as implemented in the WIEN2k package. Engel–Vosko generalized gradient approximation (EV-GGA) is employed as the exchange-correlation functional. The nanowire is modeled using a supercell approach with vacuum in two directions to simulate one-dimensional nanostructure along the [001] direction.
2：Sample Selection and Data Sources:
The calculations are based on the orthorhombic Sb2S3 crystal structure with space group Pnma (62). Lattice parameters are a = 11.646 ?, b = 3.953 ?, c = 11.587 ?. No external datasets are used; all data are generated from computational simulations.
3：2). Lattice parameters are a = 646 ?, b = 953 ?, c = 587 ?. No external datasets are used; all data are generated from computational simulations.
List of Experimental Equipment and Materials:
3. List of Experimental Equipment and Materials: Computational software: WIEN2k code. No physical equipment or materials are used as it is a theoretical study.
4：Experimental Procedures and Operational Workflow:
The unit cell is divided into muffin-tin spheres with radii RMT = 2.0 a.u. for S and 2.43 a.u. for Sb atoms. Parameters set include RMTKMAX=6, GMAX=12, cut-off energy = -6 Ry, and 15×1×1 k-points for Brillouin zone integration. Total energy convergence criterion is 0.00001 Ry. Optical properties are calculated using the modified joint density of states and random phase approximation (RPA).
5：0 a.u. for S and 43 a.u. for Sb atoms. Parameters set include RMTKMAX=6, GMAX=12, cut-off energy = -6 Ry, and 15×1×1 k-points for Brillouin zone integration. Total energy convergence criterion is 00001 Ry. Optical properties are calculated using the modified joint density of states and random phase approximation (RPA).
Data Analysis Methods:
5. Data Analysis Methods: Electronic band structure, density of states (DOS), and optical properties (dielectric function, absorption coefficient, reflectivity, refractive index, energy loss function) are analyzed. Comparisons are made with previous calculations on Sb2S3 bulk.
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