Institute of Physics, University of Tartu, 50411 Tartu, Estonia.
Department for Solar Energy, Institute for Energy Technology, 2027 Kjeller, Norway.
J Chem Phys. 2017 Feb 14;146(6):064706. doi: 10.1063/1.4975176.
Based on the combination of density functional theory and theory-group methods, we performed systematic modeling of γ-CuI structural design at the atomistic level. Being started from the metallic copper lattice, we treated a crystal assembly as a stepwise iodination process characterized in terms of a sequence of intermediate lattice geometries. These geometries were selected and validated via screening of possible structural transformations. The genesis of chemical bonding was studied for three structural transformations by analyzing the relevant changes in the topology of valence electron densities. We determined structural trends driven by metal-ligand coupling. This allowed us to suggest the improved scenario of chemical bonding in γ-CuI. In particular, the unconventional effect of spatial separation of metallic and covalent interactions was found to be very important with respect to the preferred arrangements of valence electrons in the iodination process. We rigorously showed that useful electronic and optical properties of γ-CuI originate from the combination of two separated bonding patterns-strong covalency established in I-Cu tetrahedral connections and noncovalent interactions of copper cores is caused by the 3d closed-shell electron configurations. The other finding of ours is that the self-consistency of the GW calculations is crucial for correctly determining the dynamic electronic correlations in γ-CuI. Detail reinvestigation of the quasi-particle energy structure by means of the self-consistent GW approach allowed us to explain how p-type electrical conductivity can be engineered in the material.
基于密度泛函理论和群论方法的结合，我们在原子水平上对γ-CuI 的结构设计进行了系统的建模。从金属铜晶格开始，我们将晶体组装体视为一个逐步碘化过程，其特征在于一系列中间晶格几何形状。通过筛选可能的结构转变，选择和验证了这些几何形状。通过分析价电子密度拓扑的相关变化，研究了三种结构转变的化学键形成的起源。我们确定了金属-配体耦合驱动的结构趋势。这使我们能够提出改进的γ-CuI 化学键合方案。特别是，发现金属和共价相互作用的空间分离的非常规效应对于碘化过程中价电子的优先排列非常重要。我们严格证明了γ-CuI 的有用的电子和光学性质源于两种分离的键合模式的结合-在 I-Cu 四面体连接中建立的强共价键以及由 3d 满壳层电子构型引起的铜核的非共价相互作用。我们的另一个发现是 GW 计算的自洽性对于正确确定 γ-CuI 中的动态电子相关性至关重要。通过自洽 GW 方法对准粒子能量结构进行的详细再研究使我们能够解释如何在材料中设计 p 型电导率。
