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籍SCC-DV-Xα法,用[AlO_4]~(5-)和[AlO_6]~(9-)模型计算了Al离子的轨道占有率和配位数所引起的Al Kα线化学位移。这是基于下述考虑。对[AlO_(?)]~(?)基团,相对于中性自由Al原子的Al Kα线化学位移ΔE(m),可以用下式表示。ΔE(m)=(ΔE_(3p)+ΔE_3(?)+ΔE_(3d))+ΔE。其中,ΔE_3s、ΔE_3p和ΔE_3d分别为Al离子的3s、3p和3d电子数的变化所引起的AlKα线位移,ΔE_o为O离子电场不同所引起的位移。计算结果表明:(1)4配位Al离子的3p和3d电子数显著高于6配位Al。(2)配位数不同所产生的AlKα线位移主要取决于Al离子本身的电荷量及其价电子配置。而且,此位移主要是3p电子数的变化所引起。3d电子数的变化则导致Al Kα线向相反方向位移,并且其值甚小。
Al Kα line chemical shifts caused by the orbital occupancy and coordination number of Al ions have been calculated by the model of [AlO 4] 5- (5) and [AlO 6] 9- with SCC-DV-Xα method. This is based on the following considerations. The chemical shift ΔE (m) of Al Kα relative to the neutral Al atoms can be expressed by the following equation for the [AlO_ (?)]? ΔE m = ΔE_3p + ΔE_3? + ΔE_3d + ΔE. Among them, ΔE_3s, ΔE_3p and ΔE_3d are AlKα line displacements caused by the changes of 3s, 3p and 3d electrons of Al ions, respectively, ΔE_o is the displacement caused by the different electric fields of O ions. The calculated results show that: (1) 3p and 3d electrons of 4-coordinated Al ions are significantly higher than those of 6-coordinated Al. (2) The AlKα line shift caused by the different coordination number mainly depends on the charge of Al ion and its valence electron configuration. Moreover, this displacement is mainly caused by the change of 3p electrons. The change in the 3d electron number causes the Al Kα line to shift in the opposite direction and its value is very small.