Department of Mechanical Engineering, University of Minnesota, Twin Cities, MN, 55455, USA; Department of Materials Engineering, Kasteelpark Arenberg 44, Box 2450, 3001, Leuven, Belgium.
Carbohydr Polym. 2020 Feb 15;230:115624. doi: 10.1016/j.carbpol.2019.115624. Epub 2019 Nov 16.
Objective boundary conditions are used to simulate at the atomistic scale cellulose Iβ microfibrils. The method enables for the first time a direct calculation of the structural twist from a self-consistent charge density-functional-based tight-binding description of interatomic interactions. Calculations reveal that microfibrils are stabilized under a uniform right-handed twist whose magnitude depends on the area and the shape of the microfibril cross-section. The latter behavior highlights the distinct structural effects imprinted by the complex hydrogen bonding network and the differences in the relative shear strength between the hydrogen and van der Waals interactions: While the intrachain bonding gives a disposition for severe twisting in the glycosidic linkages, the interchain hydrogen and van der Waals bonding contribute to the development of twist at the microfibril level. The interchain hydrogen bonding is much more effective than the van der Waals one in counterbalancing the intrinsic tendency for twist of the microfibril.
目的边界条件用于模拟原子尺度纤维素 Iβ微纤丝。该方法首次能够从原子间相互作用的自洽电荷密度泛函基紧束缚描述中直接计算结构扭曲。计算表明，微纤丝在均匀的右旋扭曲下稳定，其大小取决于微纤丝横截面的面积和形状。后一种行为突出了由复杂氢键网络和氢键与范德华相互作用之间相对剪切强度的差异所产生的明显结构效应：虽然链内键赋予糖苷键严重扭曲的倾向，但链间氢键和范德华键有助于在微纤丝水平上发展扭曲。与微纤丝的固有扭曲趋势相比，链间氢键的作用比范德华键更有效。
