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