Electronic and Band Structure Calculation of Wurtzite CdS Using GGA and GGA+U functionals

TL;DR

This study uses GGA and GGA+U density functional theory methods to analyze the electronic and structural properties of wurtzite CdS, achieving band gap values consistent with experimental data through U-parameter adjustments.

Contribution

It provides a detailed computational analysis of wurtzite CdS's electronic structure using GGA+U, highlighting the impact of U-parameters on band gap and density of states.

Findings

CdS is confirmed as a direct band gap semiconductor.

Adjusting U-parameters aligns the calculated band gap with experimental value.

U-parameter variation significantly influences the density of states near band edges.

Abstract

The wurtzite (wz) structure of CdS is analyzed using density functional theory within the generalized gradient approximation (GGA) and Hubbard correction (GGA+U). The total energy convergence evaluation is carried out concerning energy cut-off (ecutwfc) and k-point sampling. The geometry optimization of wz-CdS is calculated using the total energy and force minimization process, which is based on the Broyden Fletcher Goldfarb Shanno (BFGS) optimization algorithm. Bulk modulus and lattice parameters are estimated to ensure accuracy of the calculations. The electronic band structure, density of states (DOS), and projected density of states (PDOS) of wz-CdS are analyzed. The band structure calculation shows CdS as direct band gap semiconductor. The electronic correlation in CdS is altered by varying U-parameters of valence orbitals of Cd and S. The alteration of electronic correlation results in convergence of the band gap to the experimental value 2.4 eV. The alteration of U-parameter affects substantially the density of states near the band edges.