First-Principles Calculations of the Structural, Electronic, Optical, and Mechanical Properties of 21 Pyrophosphate Crystals

Pyrophosphate crystals have a wide array of applications in industrial and biomedical fields. However, fundamental understanding their electronic structure, optical, mechanical properties is still scattered incomplete. In the present research, we report comprehensive theoretical investigation 21 pyrophosphates A2M (H2P2O7)2•2H2O with either triclinic or orthorhombic crystal structure. The molecule H2P2O7 dominant molecular unit, whereas A = (K, Rb, NH4, Tl), M (Zn, Cu, Mg, Ni, Co, Mn), H2O stand for cation elements, transition metals, water molecules, respectively. interatomic bonding, partial charge distribution, optical properties, are investigated by first-principles calculations based on density functional theory (DFT). Most these theoretically first time. calculated results show complex interplay between A, M, H2P2O7, H2O, resulting metallic, half-metallic, semi-conducting characteristics. novel concept total bond order (TBOD) used as single quantum metric to characterize internal cohesion correlate especially properties. This work provides large database pyrophosphate road map potential wider variety phosphates.