Investigation of stability of two- and three-dimensional crystal structures of GeSe compound by ab-initio method

In this thesis, the structural, electronic, mechanical, thermodynamic, and thermoelectric properties of the two- and three-dimensional crystal structures of the α, β and γ phases of GeSe compound were investigated by the ab initio method based on the density functional theory. The generalized grandyen approach and the Grimme method were used to calculate the exchange correlation energy. Electronic band structures, elastic constants, polycrystalline properties of GeSe compound were calculated and interpreted. In addition, phonon dispersion and phonon density of states, thermodynamic and thermoelectric properties were studied in detail. The calculated lattice parameters are in agreement with the theoretical and experimental studies. The α, β and γ phases of the GeSe compound show mechanical and dynamic stability.