Biology and Soft Matter Division, Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831, USA.
J Chem Phys. 2012 Apr 14;136(14):144901. doi: 10.1063/1.3697479.
Based on atomistic molecular dynamics (MD) simulations, the small angle neutron scattering (SANS) intensity behavior of a single generation-4 polyelectrolyte polyamidoamine starburst dendrimer is investigated at different levels of molecular protonation. The SANS form factor, P(Q), and Debye autocorrelation function, γ(r), are calculated from the equilibrium MD trajectory based on a mathematical approach proposed in this work. The consistency found in comparison against previously published experimental findings (W.-R. Chen, L. Porcar, Y. Liu, P. D. Butler, and L. J. Magid, Macromolecules 40, 5887 (2007)) leads to a link between the neutron scattering experiment and MD computation, and fresh perspectives. The simulations enable scattering calculations of not only the hydrocarbons but also the contribution from the scattering length density fluctuations caused by structured, confined water within the dendrimer. Based on our computational results, we explore the validity of using radius of gyration R(G) for microstructure characterization of a polyelectrolyte dendrimer from the scattering perspective.
基于原子分子动力学（MD）模拟，研究了不同分子质子化程度下第一代 4 代聚电解质聚酰胺胺星型树枝状大分子的小角中子散射（SANS）强度行为。根据本工作提出的数学方法，从平衡 MD 轨迹计算 SANS 形态因子 P（Q）和 Debye 自相关函数γ（r）。与之前发表的实验结果（W.-R. Chen，L. Porcar，Y. Liu，P. D. Butler 和 L. J. Magid，Macromolecules 40, 5887（2007））进行比较时发现的一致性，在中子散射实验和 MD 计算之间建立了联系，并提供了新的视角。模拟不仅可以计算碳氢化合物的散射，还可以计算树枝状大分子中结构化受限水中散射长度密度涨落的贡献。基于我们的计算结果，我们从散射的角度探讨了使用旋转半径 R（G）来描述聚电解质树枝状大分子微观结构的有效性。
