Prediction and analysis of crystal structures of Cu2S and Cu2Se compounds using computational methods

This thesis study involved predicting the crystal structures of Cu₂S and Cu₂Se compounds. First-principles calculations, combined with the USPEX evolutionary algorithm and a well-known prototype structure search method, were employed to investigate stable phases. Theoretical calculations were performed using the Vienna Ab-initio Simulation Package (VASP) program, employing the generalized gradient approximation (GGA), Perdew–Burke–Ernzerhof (PBE) parameterizations and projected augmented wave (PAW) potentials. The calculations predicted fourteen possible phases for the Cu₂S compound and four for the Cu₂Se compound for the first time. Detailed electronic, mechanical and vibrational properties were calculated for all stable phases. These findings were then compared with existing experimental and theoretical data.