论文标题
二维离子晶体：IA-VII碱卤化物和IA-IB CSAU的病例
Two-dimensional ionic crystals: The cases of IA-VII alkali halides and IA-IB CsAu
论文作者
论文摘要
碱卤化物，称为离子晶体，具有NaCl型或CSCL型结构作为基态。我们研究了第一原理的二维（2D）离子晶体的结构，振动和电子特性。研究了两个潜在的结构，即六边形和四方作为结构模板。通过声子分散计算，六角形和四方结构中的20个碱卤化物中有8和16分别动态稳定。电子能量差距从LIF的6.8 eV到在广义梯度近似中的四方结构中的RBI和CSI的3.9 eV范围。通过考虑Madelung的能量和核心核心排斥，我们提出了一个硬球模型，该模型是最接近的邻居键长度和2D碱卤化物的凝聚力。四方结构中的2D CSAU也被预测为一个离子晶体稳定，其中包括金属元素，显示的带状隙为2.6 eV，高于3D对应物的带隙。
The alkali halides, known as ionic crystals, have the NaCl-type or CsCl-type structure as the ground state. We study the structural, vibrational, and electronic properties of two-dimensional (2D) ionic crystals from first-principles. Two potential structures that are hexagonal and tetragonal are investigated as structural templates. Through phonon dispersion calculations, 8 and 16 out of 20 alkali halides in the hexagonal and tetragonal structures are dynamically stable, respectively. The electron energy gaps range from 6.8 eV for LiF to 3.9 eV for RbI and CsI in the tetragonal structure within the generalized gradient approximation. By considering the Madelung energy and the core-core repulsion, we propose a hard sphere model that accounts for the nearest-neighbor bond length and the cohesive energy of 2D alkali halides. The 2D CsAu in the tetragonal structure is also predicted to be stable as an ionic crystal including only metallic elements, showing a band gap of 2.6 eV that is higher than that of the 3D counterparts.
