In-Depth DFT-Based Analysis of the Structural, Mechanical, Thermodynamic, and Electronic Characteristics of CuP2 and Cu3P: Insights into Material Stability and Performance

This study employed density functional theory (DFT) to investigate the structural, mechanical, thermodynamic, and electronic properties of monoclinic CuP2 and hexagonal Cu3P. The analysis confirmed the mechanical stability of both compounds, with distinct anisotropic behaviors arising from crystallographic symmetries. Cu3P exhibits a higher bulk modulus (130.1 GPa), indicating superior resistance to volumetric compression, while CuP2 demonstrates greater shear (52.9 GPa) and Young’s moduli (133.3 GPa), reflecting enhanced stiffness and tensile resistance. The K/G ratio (1.749 for CuP2 vs. 3.120 for Cu3P) and Cauchy pressure analyses revealed the brittle nature of CuP2, with covalent bonding, and the ductility of Cu3P, with metallic bonding. The thermodynamic evaluations highlighted the higher Debye temperature of CuP2 (453.1 K) and its lattice thermal conductivity (8.37 W/mK), suggesting superior heat dissipation, whereas Cu3P shows greater thermal expansion (38.4 × 10−6/K) and a higher volumetric heat capacity (3.29 × 106 J/m3K). The electronic structure calculations identified CuP2 as a semiconductor with a 0.824 eV bandgap and Cu3P as a conductor with metallic states at the Fermi level. These insights are critical for optimizing Cu-P compounds in microelectronic packaging, where thermal management and mechanical reliability are paramount.