https://doi.org/10.1140/epjb/e2008-00193-x
First principles calculations of structural, electronic and optical properties of various phases of CaS
1
Department of Physics, G. C. University, Faisalabad, 38000, Pakistan
2
Center for Solid State Physics, Punjab University, Lahore, 54590, Pakistan
3
Department of Physics, Isfahan University of Technology, Isfahan, 84156, Iran
Corresponding author: a schaukat@gmail.com
Received:
24
January
2008
Revised:
8
April
2008
Published online:
22
May
2008
First principles calculations have been performed within the framework of density functional theory to investigate the structural, electronic and optical properties of all four possible B1, B2, B3 and B4 phases of CaS. Apart from the standard local density approximation (LDA) and GGA (PBE), a more accurate nonempirical density functional generalized gradient approximation (GGA), as proposed by Wu and Cohen [Phys. Rev. B 73, 235116 (2006)] for the exchange-correlation energy, EXC, has been attempted in these calculations. Calculated electronic structure and the density of states are analyzed in terms of the contribution of Ca d states and S s and p states in determining the nature of the fundamental band gap in various phases. Reflectivity, R (ω), the real and imaginary part of the dielectric functions, ε(ω), have been calculated for all the phases and the results have been discussed and compared with the existing experimental data.
PACS: 71.15.Mb – Density functional theory, local density approximation, gradient and other corrections / 74.25.Gz – Optical properties / 74.25.Jb – Electronic structure
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2008