Band structure and properties of a new crystal of the chalcopyrite family: LiGaSe2

Within the framework of density functional theory using hybrid functionals, the energy band structure and phonon spectrum of the LiGaSe₂ (LGSe) semiconductor with a chalcopyrite structure have been obtained ab initio. The equilibrium parameters of the crystal lattice a = 5.61265 Å, c = 9.18515 Å, u = 0.2597 and the value of the direct band gap E_g = 2.21 eV have been calculated. Using the sublattice method, the origin of the bands in the crystal from the Li, Ga, Se sublattices and cationic tetrahedra LiSe₄ and GaSe₄ has been established. For long-wavelength oscillation frequencies at the Γ point, the contributions of individual atomic vibrations to the vibrational modes of the crystal have been determined. A map of the deformation density of the valence electron charge distribution has been obtained. The elastic moduli, Poisson's ratio, and microhardness generally characterize the LiGaSe₂ semiconductor as mechanically stable but soft and ductile material.