Study of phase transitions and lattice dynamics, elastic and electronic properties, bonding and weak interactions analysis of YCuS2 in P212121, I4‾2d and P4‾21m space group structures

The present work shows several physical behaviors of YCuS 2 that are still unknown, such as electronic properties, phase transitions, mechanical properties and several dynamical behaviors. This study has shown that YCuS 2 is elastically stable in the three studied structures (P2 1 2 1 2 1 , P-42 1 m and I-42d), while it is dynamically stable in P2 1 2 1 2 1 structure only, which shows that this latter is that of the ground state and the rest (P-42 1 m and I-42d) are those of phase transitions. For P2 1 2 1 2 1 structure, the found lattice parameters are very close to those of experimental and theoretical ones. Electronic properties have shown that YCuS 2 is a semiconductor in all three studied structures with a slightly wider band-gap for P2 1 2 1 2 1 structure. These results highlight the optoelectronic importance of this compound. The dynamical study of YCuS 2 has been carried out taking into consideration the LO/TO splitting. The zone-center modes have been presented. Bonding analysis using QTAIM has shown the presence of an intermediate bonding type between the different atoms, while the different weak interactions have been identified and located by NCI method. • YCuS 2 is a semiconductor in P2 1 2 1 2 1 , P-42 1 m and I-42d structures. • YCuS 2 is elastically anisotropic and dynamically stable in P2 1 2 1 2 1 structure. • Bonds between the different atoms are of an intermediate type.