Application of the three body force shell model to the lattice dynamics of calcium oxide

The lattice dynamics of GaO has been studied on the basis of the three body force shell model, which takes into account the effect of many body interactions in the lattice potential. The dispersion curves obtained by plottingω vsq agree fairly well with the experiments. It is concluded that the value of the molecular electronic polarizability of the solid must be must small than that determined experimentally which suggests that the interaction system in the solid may have a substantial covalent character.     

利用电子结构数据拟合H2分子的电子壳模型势函数参数

电子壳模型势函数在离子晶体的原子级计算机模拟中有广泛应用,其势参数主要通过拟合晶体的实验数据或电子结构数据得到.提出了通过拟合双原子分子的量子化学从头计算电子结构数据来获得该势函数的方法,并由H2分子的电子结构数据建立了H原子间的电子壳模型势函数.此外,还应用该势函数对H+2分子离子进行了计算.该势函数拟合方案更适合于共价键型的分子.     

Structure of unstable nuclei in the sd-pf shell region by shell model with proper tensor force

Focusing on the importance of the tensor force in the effective interaction, we investigate the structure of unstable nuclei around N=28 with large-scale shell-model calculations. From the analysis of the spin-tensor decomposition for some interactions, the tensor force in the effective interaction should be close to the π+ ρ force, whereas it is much weaker in the Millener-Kurath (MK) interaction which is often used as the cross-shell interaction. The significance of the tensor force appears in the structure around ⁴²Si: the proper tensor force predicts that it is deformed contrary to the result from MK.     

Surface chemistry and catalysis of oxide model catalysts from single crystals to nanocrystals

Fundamental understandings of surface chemistry and catalysis of solid catalysts are of great importance for the developments of efficient catalysts and corresponding catalytic processes, but have been remaining as a challenge due to the complex nature of heterogeneous catalysis. Model catalysts approach based on catalytic materials with uniform and well-defined surface structures is an effective strategy. Single crystals-based model catalysts have been successfully used for surface chemistry studies of solid catalysts, but encounter the so-called “materials gap” and “pressure gap” when applied for catalysis studies of solid catalysts. Recently catalytic nanocrystals with uniform and well-defined surface structures have emerged as a novel type of model catalysts whose surface chemistry and catalysis can be studied under the same operational reaction condition as working powder catalysts, and they are recognized as a novel type of model catalysts that can bridge the “materials gap” and “pressure gap” between single crystals-based model catalysts and powder catalysts. Herein we review recent progress of surface chemistry and catalysis of important oxide catalysts including CeO₂, TiO₂ and Cu₂O acquired by model catalysts from single crystals to nanocrystals with an aim at summarizing the commonalities and discussing the differences among model catalysts with complexities at different levels. Firstly, the complex nature of surface chemistry and catalysis of solid catalysts is briefly introduced. In the following sections, the model catalysts approach is described and surface chemistry and catalysis of CeO₂, TiO₂ and Cu₂O single crystal and nanocrystal model catalysts are reviewed. Finally, concluding remarks and future prospects are given on a comprehensive approach of model catalysts from single crystals to nanocrystals for the investigations of surface chemistry and catalysis of powder catalysts approaching the working conditions as closely as possible.