Periodic Density Functional Theory (PDFT) Predicting the Structure and Bonding Strength of Dehydrated Alkaline-Earth
1Institute of Molecular Sciences and Engineering, Institute of Frontier Chemistry, School of Chemistry and Chemical Engineering, Shandong University, Qingdao 266237, China.
Abstract:
Ion-exchanged chabazites have wide applications in industry. In this study, dehydrated Be2+, Mg2+, Ca2+, Sr2+, and Ba2+-exchanged chabazite sieves (CHA-M) were designed, which differ from some reported natural and hydrated chabazite mineral series. Their crystal structures and electronic properties were carefully predicted using the PDFT//PBE+TS/HI method. Each CHA-M deviates from the space group R-3M slightly. The calculated crystal volume of CHA-M was underestimated by up to -3.28% relative to the related chabazite mineral. The alkaline-earth metal cation (M2+) with the Bader charge of +1.67 ~ +1.72 e gradually moves to the center of the 8MR window of the CHA framework as the atomic number increases. The predicted HOBO-LUBO gap of CHA-M ranges from 3.74 to 5.33 eV. The alkaline-earth metal atom serves as the primary electron-accepting site in CHA-M. The M2+-[CHA]2- bond is assumed to have an -ICOHP value ranging from 0.327 to 4.005 eV and a BDE value ranging from 4.61 to 8.75 eV. Contrary to CHA-Mg, CHA-Be is likely to exhibit the highest HOBO-LUBO gap, the strongest bonding strength between M2+ and [CHA]2-, and the biggest absolute value of Fermi energy (i.e., -2.193 eV) among the five species. This study may help researchers to design new zeolites.
More Related Videos
07:20Discovery and Synthesis Optimization of Isoreticular Al(III) Phosphonate-Based Metal-Organic Framework Compounds Using High-Throughput Methods
Published on: October 6, 2023
10:42Combining Solid-state and Solution-based Techniques: Synthesis and Reactivity of Chalcogenidoplumbates(II or IV)
Published on: December 29, 2016
Related Concept Videos
02:42Ionic Crystal Structures
Most monatomic ions behave as charged spheres, and their attraction for ions of opposite charge is the same in every direction. Consequently, stable structures for ionic compounds result (1) when ions of one charge are surrounded by as many ions as possible of the opposite...
02:46Crystal Field Theory - Tetrahedral and Square Planar Complexes
Crystal field theory (CFT) is applicable to molecules in geometries other than octahedral. In octahedral complexes, the lobes of the dx2−y2 and dz2 orbitals point directly at the ligands. For tetrahedral complexes, the d orbitals remain in place, but with only four ligands located between the axes. None of the orbitals points directly at the tetrahedral ligands. However, the dx2−y2 and dz2 orbitals (along the Cartesian axes) overlap with the ligands less than the dxy,...
02:58Crystal Field Theory - Octahedral Complexes
To explain the observed behavior of transition metal complexes (such as colors), a model involving electrostatic interactions between the electrons from the ligands and the electrons in the unhybridized d orbitals of the central metal atom has been developed. This electrostatic model is crystal field theory (CFT). It helps to understand, interpret, and predict the colors, magnetic behavior, and some structures of coordination compounds of transition metals.
CFT focuses on...
02:48Ionic Bonding and Electron Transfer
01:27The Debye–Hückel Theory of Electrolyte Solutions
01:26Imperfections in Crystal Structure: Stoichiometric Point Defects