超导二硅化物多晶型物YIr2Si2的稳定性、结构、弹性和电子性质
Stability, structural, elastic and electronic properties of polymorphs of the superconducting disilicide YIr2Si2
摘要：
使用从头算方法，比较稳定性，结构，弹性和电子性能的三个多晶型的超导二硅化物YIr 2Si 2，不同的原子配置的[Ir 2Si 2]（或[Si 2 Ir 2]）块，进行了检查。对于这些YIr 2Si 2多晶型，优化的结构数据，弹性参数，电子能带，总的和部分态密度，费米表面拓扑结构，和化学键已经获得和分析。我们的研究表明，虽然ThCr 2Si 2型和CaBe 2Ge 2型多晶型物是机械稳定的，相对较硬的材料，具有低压缩性，但它们将表现为韧性系统。其中，ThCr 2Si 2型多晶型物将显示增强的弹性各向异性。在费米能附近，不同多晶型的电子能带和费米面的拓扑结构有很大的不同。此外，CaBe 2Ge 2型多晶型物预计是各向异性的，即主要发生在[Si 2 Ir 2]块中。YIr 2Si 2多晶型物相的原子间键合可以被描述为共价、金属和离子贡献的各向异性混合物，其中在[Ir 2Si 2]（或[Si 2 Ir 2]）块之间，Ir-Si和Ir-Ir键发生，而在相邻的[Ir 2Si 2]之间，（或[Si 2 Ir 2]）块和Y原子片，Si-Si和Ir-Y，Si-Ir和Si-Y，或主要是Ir-Ir键出现的各种多晶型。
英文摘要：
Using the ab initio approaches, the comparative stability, structural, elastic, and electronic properties of three polymorphs of the superconducting disilicide YIr2Si2, which differ in the atomic configurations of [Ir2Si2] (or [Si2Ir2]) blocks, were examined. For these YIr2Si2 polymorphs, the optimized structural data, elastic parameters, electronic bands, total and partial densities of states, Fermi surface topology, and chemical bonding have been obtained and analyzed. Our studies showed that although ThCr2Si2- and CaBe2Ge2-type polymorphs are mechanically stable and relatively hard materials with low compressibility, they will behave as ductile systems. Among them, ThCr2Si2-type polymorph will show enhanced elastic anisotropy. In the vicinity of the Fermi energy, the topology of the electronic bands and the Fermi surface for various polymorphs are quite different. Besides, the CaBe2Ge2-type polymorph is expected to be anisotropic, i.e. happening mainly in the [Si2Ir2] blocks. The inter-atomic bonding for YIr2Si2 polymorph phases can be described as an anisotropic mixture of covalent, metallic, and ionic contributions, where inside the [Ir2Si2] (or [Si2Ir2]) blocks, Ir-Si and Ir-Ir bonds take place, whereas between the adjacent [Ir2Si2] (or [Si2Ir2]) blocks and Y atomic sheets, Si-Si and Ir-Y, Si-Ir and Si-Y, or mainly Ir-Ir bonds emerge for various polymorphs.
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