First principles calculations of structural, electronic and optical properties of various phases of CaS

• Published in: The European physical journal. B, Condensed matter physics Vol. 62; no. 4; pp. 439 - 446
• Main Authors: Shaukat, A., Saeed, Y., Ikram, N., Akbarzadeh, H.
• Format: Journal Article
• Language: English
• Published: Les Ulis EDP Sciences 01.04.2008; Springer; EDP sciences
• Subjects: Complex Systems; Condensed Matter Physics; Condensed matter: electronic structure, electrical, magnetic, and optical properties; Electron density of states and band structure of crystalline solids; Electron states; Exact sciences and technology; Fluid- and Aerodynamics; Methods of electronic structure calculations; Optical properties and condensed-matter spectroscopy and other interactions of matter with particles and radiation; Optical properties of bulk materials and thin films; Other inorganic compounds; Physics; Physics and Astronomy; Solid State Physics; Solids and Liquids; 71.15.Mb Density functional theory, local density approximation, gradient and other corrections; 74.25.Gz Optical properties; 74.25.Jb Electronic structure; Reflectivity; Dielectric function; Electronic structure; Reflection spectrum; Optical properties; Calcium sulfide; Density functional method; Generalized gradient approximation; Electronic density of states; Exchange interactions; Local density approximation
• ISSN: 1434-6028; 1434-6036
• DOI: 10.1140/epjb/e2008-00193-x

. 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, E XC , 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.