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探讨和比较了确定金属氧化物晶体点电荷量的几种自洽条件的优劣 ,并使用abinitioHF方法对在不同点电荷量嵌入环境下MgO簇电子性质进行了研究 .计算结果表明 :点电荷量的大小会明显影响嵌入簇的电子性质 ;即使MgO被通常认为是纯的离子型氧化物 ,点电荷量取为表观化合价± 2 ,仍过高地估计了Madelung势 ,嵌入簇与点电荷之间应满足一定的自洽条件 ;使用点电荷为嵌入环境时 ,即使达到电荷自洽、偶极矩自洽或势自洽 ,簇模型计算结果仍与固体性质存在一定的偏差 ;将点电荷进行球谐展开 ,赋予其连续变化的电荷密度分布后 ,得到了一个对固体整体性质描述较好的SPC簇模型 .
The advantages and disadvantages of several self-consistent conditions for determining point charge of metal oxide crystals are discussed and compared, and the electronic properties of MgO clusters under different charge amount embedding conditions are studied by using abinitioHF method. The calculated results show that the point charge amount The size of the cluster will significantly affect the electronic properties of embedded clusters. Even though MgO is generally considered to be a pure ionic oxide, the point charge is taken as the apparent valence of ± 2, the Madelung potential is still overestimated, Should satisfy certain self-consistent conditions; when the point charge is used as the embedded environment, the calculated result of the cluster model still has a certain deviation from the solid property even if the self-consistent charge or the self-consistent dipole moment is reached; After the harmonic expansion, given its continuous changes in the charge density distribution, a good description of the overall properties of the solid SPC cluster model.