Hempelmann Jan, Müller Peter C, Ertural Christina, Dronskowski Richard
Institute of Inorganic Chemistry, RWTH Aachen University, Landoltweg 1, 52056, Aachen, Germany.
Jülich-Aachen Research Alliance (JARA-CSD), RWTH Aachen University, 52056, Aachen, Germany.
Angew Chem Int Ed Engl. 2022 Apr 19;61(17):e202115778. doi: 10.1002/anie.202115778. Epub 2022 Feb 2.
Layered phase-change materials in the Ge-Sb-Te system are widely used in data storage and are the subject of intense research to understand the quantum-chemical origin of their unique properties. To uncover the nature of the underlying periodic wavefunction, we have studied the interacting atomic orbitals including their phases by means of crystal orbital bond index and fragment crystal orbital analysis. In full accord with findings based on projected force constants, we demonstrate the role of multicenter bonding along straight atomic connectivities. While the resulting multicenter bonding resembles three-center-four-electron bonding in molecules, its solid-state manifestation leads to distinct long-range consequences, thus serving to contextualize the material properties usually termed "metavalent". Eventually we suggest multicenter bonding to be the origin of their astonishing bond-breaking and phase-change behavior, as well as the too small "van-der-Waals" gaps between individual layers.
锗锑碲体系中的层状相变材料在数据存储中广泛应用，并且是深入研究以理解其独特性质的量子化学起源的主题。为了揭示潜在周期性波函数的本质，我们借助晶体轨道键指数和片段晶体轨道分析研究了相互作用的原子轨道，包括它们的相位。与基于投影力常数的研究结果完全一致，我们证明了沿直线原子连接性的多中心键合的作用。虽然由此产生的多中心键合类似于分子中的三中心四电子键合，但其固态表现会导致明显的长程结果，从而有助于解释通常称为“准价”的材料特性。最终，我们认为多中心键合是其惊人的断键和相变行为以及各层之间过小的“范德华”间隙的起源。
