Computational studies on chemical properties of solid-state materials and important solid-phase chemical processes have been reported in thesis. Chapter Two reports a systematic study about the influence of gauche effect of P-P bonds on the relative stability among 2D phosphorus allotropes. This work revealed that the better stability of 2D violet phosphorus over other 2D phosphorus allotropes comes from the fact that 2D violet phosphorus has the highest proportion of P-P bonds under gauche conformation, the most energetically favorable P-P bond conformation, than other 2D phosphorus allotropes. And through orbitalwise integrated crystal orbital Hamilton population analysis, this work verified that the stability of gauche P-P bonds results from the minimized repulsion between the two ne...[ Read more ]

Computational studies on chemical properties of solid-state materials and important solid-phase chemical processes have been reported in thesis. Chapter Two reports a systematic study about the influence of gauche effect of P-P bonds on the relative stability among 2D phosphorus allotropes. This work revealed that the better stability of 2D violet phosphorus over other 2D phosphorus allotropes comes from the fact that 2D violet phosphorus has the highest proportion of P-P bonds under gauche conformation, the most energetically favorable P-P bond conformation, than other 2D phosphorus allotropes. And through orbitalwise integrated crystal orbital Hamilton population analysis, this work verified that the stability of gauche P-P bonds results from the minimized repulsion between the two neighboring lone pairs when the bond torsion is around 70~90°. Chapter Three presents a research work to investigate the reasons leading to the high conductivity of a newly synthesized 2D Covalent-Organic framework (COF) film from the perspective electronic structure. Our results indicated that the improved matching between the LUMO of the metal-porphyrin moiety and the LUMO of the applied linkage moiety leads to the formation of an enhanced donor–acceptor system which allows the excited electrons in metal-porphyrin center to facilely flow into the unoccupied orbitals of the applied linkage moieties. Bonding analysis showed that, apart from interlayer π-π stacking, interlayer metal-metal bonds also exist, and that 2D COFs with different kinds of metal centers have some subtle differences in terms of the characteristics of the interlayer metal-metal bonds. Chapter Four covers our metadynamics simulation of the δ- to α-CsPbI₃ transformation at elevated temperature. The results of our simulation clearly showed that, throughout the process, δ-CsPbI₃ underwent two stages of movements, the intrachain rearrangement stage and then the interchain connection stage, to transform into α-CsPbI₃. The dynamics of different types of atoms of the Pb-I framework in these two stages were elucidated clearly through our detailed statistical analysis. The dynamic behavior of Cs⁺ cations was observed to possibly facilitate the interchain connection stage of the transformation.