Department of Materials Science and Engineering and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States.
Department of Physics and Astronomy and Ames Laboratory, Iowa State University , Ames, Iowa 50011, United States.
ACS Nano. 2017 Nov 28;11(11):11273-11282. doi: 10.1021/acsnano.7b05694. Epub 2017 Oct 31.
We present a detailed analysis of the interaction between two nanocrystals capped with ligands consisting of hydrocarbon chains by united atom molecular dynamics simulations. We show that the bonding of two nanocrystals is characterized by ligand textures in the form of vortices. These results are generalized to nanocrystals of different types (differing core and ligand sizes) where the structure of the vortices depends on the softness asymmetry. We provide rigorous calculations for the binding free energy, show that these energies are independent of the chemical composition of the cores, and derive analytical formulas for the equilibrium separation. We discuss the implications of our results for the self-assembly of single-component and binary nanoparticle superlattices. Overall, our results show that the structure of the ligands completely determines the bonding of nanocrystals, fully supporting the predictions of the recently proposed Orbifold topological model.
我们通过联合原子分子动力学模拟，对由碳氢链配体覆盖的两个纳米晶体之间的相互作用进行了详细分析。我们表明，两个纳米晶体的键合特征是涡旋形式的配体纹理。这些结果被推广到不同类型的纳米晶体（不同的核心和配体尺寸），其中涡旋的结构取决于柔软度的不对称性。我们对结合自由能进行了严格的计算，表明这些能量与核心的化学成分无关，并推导出了平衡分离的解析公式。我们讨论了我们的结果对单组分和二元纳米粒子超晶格自组装的影响。总的来说，我们的结果表明，配体的结构完全决定了纳米晶体的键合，完全支持了最近提出的 Orbifold 拓扑模型的预测。
