Li Haisheng, Chen Weiguang, Han Xiaoyu, Li Liben, Sun Qiang, Guo Zhengxiao, Jia Yu
School of Physics and Engineering, Henan University of Science and Technology, Luoyang City, Henan Province, 471023, China.
Center for Clean Energy and Quantum Structures, and School of Physics and Engineering, Zhengzhou University, Zhengzhou, 450001, China.
J Comput Chem. 2015 Sep 30;36(25):1919-27. doi: 10.1002/jcc.24028. Epub 2015 Aug 12.
Van der Waals (vdW) interactions play an important role on semiconductors in nanoscale. Here, we utilized first-principles calculations based on density functional theory to demonstrate the growth mode transition from prolate to multiunit configurations for Gen (n = 10-50) clusters. In agreement with the injected ion drift tube techniques that "clusters with n < 70 can be thought of as loosely bound assemblies of small strongly bound fragments (such as Ge7 and Ge10 )," we found these stable fragments are connected by Ge6 , Ge9 , or Ge10 unit (from bulk diamond), via strong covalent bonds. Our calculated cations usually fragment to Ge7 and Ge10 clusters, in accordance with the experiment results that the spectra Ge7 and Ge10 correspond to the mass abundance spectra. By controlling a germanium cluster with vdW interactions parameters in the program or not, we found that the vdW effects strengthen the covalent bond from different units more strikingly than that in a single unit. With more bonds between units than the threadlike structures, the multiunit structures have larger vdW energies, explaining why the isolated nanowires are harder to produce. © 2015 Wiley Periodicals, Inc.
范德华（vdW）相互作用在纳米尺度的半导体中起着重要作用。在此，我们利用基于密度泛函理论的第一性原理计算，证明了Gen（n = 10 - 50）团簇从长形到多单元构型的生长模式转变。与注入离子漂移管技术一致，即“n < 70的团簇可被视为由小的强束缚碎片（如Ge7和Ge10）松散结合而成的组装体”，我们发现这些稳定的碎片通过Ge6、Ge9或Ge10单元（来自体相金刚石）经由强共价键相连。我们计算得出的阳离子通常会裂解为Ge7和Ge10团簇，这与实验结果相符，即Ge7和Ge10的光谱对应于质量丰度光谱。通过在程序中控制具有范德华相互作用参数的锗团簇，我们发现范德华效应比在单个单元中更显著地增强了不同单元之间的共价键。由于单元之间的键比线状结构更多，多单元结构具有更大的范德华能量，这解释了为什么孤立的纳米线更难产生。© 2015威利期刊公司。
