Schwan Sebastian, Klee Benjamin D, Rinn Niklas, Schreiner Peter R, Dehnen Stefanie, Pilgrim Wolf-Christian, Mollenhauer Doreen
Institute of Physical Chemistry, Justus Liebig University, Heinrich-Buff-Ring 17, Giessen 35392, Germany.
Center for Materials Research, Justus Liebig University, Heinrich-Buff-Ring 16, Giessen 35392, Germany.
J Chem Theory Comput. 2024 Sep 10;20(17):7586-7596. doi: 10.1021/acs.jctc.4c00196. Epub 2024 Aug 29.
Cluster materials of the composition AdR (Ad = adamantane, R = organic substituent) and [(RT)E] (R = organic substituent; T = Si, Ge, Sn; and E = S, Se, Te) exhibit directional white light emission or produce second harmonics when irradiated with a continuous wave infrared laser source. The nature of the nonlinear optical properties correlates with the macroscopic structures of the cluster materials. The desired white light emission predominantly occurs in amorphous materials. It is therefore crucial to understand the geometric structures of the materials and the order within the materials. Here, we investigate the geometric structures of 12 different adamantane-like cluster materials by molecular dynamics simulations using a nonperiodic particle approach. The comparison of the calculated structure factors for two cluster materials with the corresponding experimental data obtained from diffraction and EXAFS measurements shows very good agreement. Our computations revealed that, on the one hand, larger, more flexible core structures (Ad < {SiS} < {GeS} < {SnS}) tend to lead to amorphous solids. On the other hand, larger substituents (methyl < phenyl < naphthyl) lead to more defined nearest neighbor interactions, with a tendency toward crystalline solids. Overall, our results show that a beginning order in the material results from a combination of the degree of flexibility of the core structure and the variation of the nearest neighbor interaction determined by the substituents.
组成成分为AdR（Ad = 金刚烷，R = 有机取代基）和[(RT)E]（R = 有机取代基；T = Si、Ge、Sn；E = S、Se、Te）的簇状材料在连续波红外激光源照射下表现出定向白光发射或产生二次谐波。非线性光学性质的本质与簇状材料的宏观结构相关。所需的白光发射主要发生在非晶态材料中。因此，了解材料的几何结构和材料内部的有序性至关重要。在这里，我们使用非周期性粒子方法通过分子动力学模拟研究了12种不同的类金刚烷簇状材料的几何结构。两种簇状材料计算得到的结构因子与从衍射和EXAFS测量获得的相应实验数据的比较显示出非常好的一致性。我们的计算表明，一方面，更大、更灵活的核心结构（Ad < {SiS} < {GeS} < {SnS}）倾向于形成非晶态固体。另一方面，更大的取代基（甲基 < 苯基 < 萘基）导致更明确的近邻相互作用，有形成结晶固体的趋势。总体而言，我们的结果表明，材料中的初始有序性是由核心结构的灵活程度和由取代基决定的近邻相互作用的变化共同导致的。
