Benyoucef haddou, miloud2024-03-172024-03-172022https://theses.univ-temouchent.edu.dz/opac_css/doc_num.php?explnum_id=4918http://dspace.univ-temouchent.edu.dz/handle/123456789/3008Condensed matter physics and materials science include many important areas such as the study of metals, semi- metals, half-metals and semiconductors. These materials play an increasingly important role in technological applications, and this role will only increase in many areas. In this work, we studied the Electronic Structure and Optical Properties of the Ternary Chalcogenide Compound Cu2 Ge S3 using First Principle Calculations We applied the density functional theory (DFT) approach and its two approximations to the exchange and correlation energy: the local density approximation (LDA) and the generalized gradient approximation ( GGA). The basic formalism of DFT is based on the Hohenberg-Kohn theorem. This approach applies to any system with several interacting particles evolving in an external potential, implemented in the wien2k code. The results of the structural and electronic properties are in good agreement with the experimental results.