Building up Complexity from Strips and Sheets: The Electronic Structure of the La12Mn2Sb30Alloy
Building up Complexity from Strips and Sheets: The Electronic Structure of the La12Mn2Sb30Alloy
复制标题
从带材和片材构建复杂性：La12Mn2Sb30合金的电子结构
DOI：
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发表时间：
1998
期刊：
影响因子：
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通讯作者：
R. Hoffmann
中科院分区：
文献类型：
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作者：
G. Papoian;R. Hoffmann
The bonding in the relatively complex La{sub 12}Mn{sub 2}Sb{sub 30} alloy structure is analyzed with a retrotheoretical/building up process, implemented through a molecular orbital analysis of the various sublattices and the composite structure. In the antimony part of La{sub 12}Mn{sub 2}Sb{sub 30} there are three relatively noninteracting networks: a three-dimensional Sb{sub 20} sublattice, an Sb{sub 6} strip, and a one-dimensional array of isolated Sb atoms (of Sb{sub 4} stoichiometry). A Zintl-type approach, modified for the clearly hypervalent nature of locally linear and square-planar Sb environments, leads to an initial partitioning of the electrons among the Sb sublattices; this electron counting eventually turns out to be in reasonable agreement with extended Hueckel calculations. The electronic structure of the three-dimensional Sb{sub 20} sublattice in La{sub 12}Mn{sub 2}Sb{sub 30} is derived theoretically from a two-dimensional square Sb sheet through first kinking the square sheet at every fifth diagonal line and then stacking the sheets, with Sb-Sb bond formation, into the third dimension. For the Sb{sub 6} strips a second-order Peierls-type distortion of symmetrical vertex-sharing rhombi leads to the slightly asymmetrical strip structure observed. The d-block splitting of the Mn ions (in an unusual bicapped tetrahedral Sb environment) is described by a molecular model;more » arguments are given for localized bonding at Mn. There are significant La-Sb network interactions. The ability of the Sb networks in this structure to act as electron reservoirs is supported by the calculations.« less
The bonding in the relatively complex La{sub 12}Mn{sub 2}Sb{sub 30} alloy structure is analyzed with a retrotheoretical/building up process, implemented through a molecular orbital analysis of the various sublattices and the composite structure. In the antimony part of La{sub 12}Mn{sub 2}Sb{sub 30} there are three relatively noninteracting networks: a three-dimensional Sb{sub 20} sublattice, an Sb{sub 6} strip, and a one-dimensional array of isolated Sb atoms (of Sb{sub 4} stoichiometry). A Zintl-type approach, modified for the clearly hypervalent nature of locally linear and square-planar Sb environments, leads to an initial partitioning of the electrons among the Sb sublattices; this electron counting eventually turns out to be in reasonable agreement with extended Hueckel calculations. The electronic structure of the three-dimensional Sb{sub 20} sublattice in La{sub 12}Mn{sub 2}Sb{sub 30} is derived theoretically from a two-dimensional square Sb sheet through first kinking the square sheet at every fifth diagonal line and then stacking the sheets, with Sb-Sb bond formation, into the third dimension. For the Sb{sub 6} strips a second-order Peierls-type distortion of symmetrical vertex-sharing rhombi leads to the slightly asymmetrical strip structure observed. The d-block splitting of the Mn ions (in an unusual bicapped tetrahedral Sb environment) is described by a molecular model;more » arguments are given for localized bonding at Mn. There are significant La-Sb network interactions. The ability of the Sb networks in this structure to act as electron reservoirs is supported by the calculations.« less