Koc, H.Ozisik, H.Deligoz, E.Mamedov, A. M.Özbay, Ekmel2015-07-282015-07-2820141610-2940http://hdl.handle.net/11693/12406The structural, mechanical, electronic, and optical properties of orthorhombic Bi2S3 and Bi2Se3 compounds have been investigated by means of first principles calculations. The calculated lattice parameters and internal coordinates are in very good agreement with the experimental findings. The elastic constants are obtained, then the secondary results such as bulk modulus, shear modulus, Young's modulus, Poisson's ratio, anisotropy factor, and Debye temperature of polycrystalline aggregates are derived, and the relevant mechanical properties are also discussed. Furthermore, the band structures and optical properties such as real and imaginary parts of dielectric functions, energy-loss function, the effective number of valance electrons, and the effective optical dielectric constant have been computed. We also calculated some non-linearities for Bi2S3 and Bi2Se3 (tensors of elasto-optical coefficients) under pressureEnglishBi2S3Band StructureBi2se3Elastic ConstantsMechanical PropertiesOptical PropertiesBismuth Sulfide NanoparticlesDensity-functional TheoryTotal-energy CalculationsAugmented-wave MethodAb InitioTopological InsulatorsThin-filmsElastic-constantsMolecular-dynamicsBasis-setArticle10.1007/s00894-014-2180-1