标题： 冰-水界面处的冰活性溶液的分子动力学 显示英文标题

标题： Molecular dynamics of ice-active solutions at ice-water interfaces

摘要： 与水强烈相互作用的小分子是本次分子动力学（MD）研究的主题。 这些溶质包括一种冷冻保护剂（DMSO），一种多元醇 [CH$_2$(OH)$_2$]，羧酸共轭物（HCOOH 和 HCOONa），一种铵盐（NH$_4$Cl），以及两种烷基卤化物盐（NaCl 和 NaF）。 对过冷液体和与冰接触的溶液进行了MD模拟。 比较了体相和作为溶质分子距离函数的溶质和水的氢键、取向和平动有序性，以及氢键跳跃动力学。 使用反向非平衡分子动力学（RNEMD）模拟来确定界面宽度、与冰的摩擦系数（$\kappa$）和溶液相粘度（$\eta$）。 发现离子溶质会降低冰界面附近的取向和平动有序性。 然而，在体相液体中，我们发现取向有序性和水氢键统计之间存在相关性——水中的供体-受体不平衡对体相液体的有序性影响最大。 尽管离子溶液对水结构有类似的影响，但对动力学的影响最直接地取决于供体-受体不平衡。 发现作为氢键受体的溶质相对于氢键供体会减慢氢键寿命。 我们还观察到液相氢键跳跃时间和剪切粘度之间有直接相关性。 最后，在所有研究的溶质中，只有DMSO和甲酸钠在冰-水界面上表现出增加的摩擦力。 显示英文摘要

摘要： Small molecules that interact strongly with water were the subject of this molecular dynamics (MD) study. These solutes include a cryoprotectant (DMSO), a polyalcohol [CH$_2$(OH)$_2$], carboxylic acid conjugates (HCOOH and HCOONa), an ammonium salt (NH$_4$Cl), and two alkyl halide salts (NaCl and NaF). MD simulations were carried out for bulk supercooled liquids and solutions in contact with ice. Solute and water hydrogen bonding, orientational and translational order, and hydrogen bond jump dynamics were compared in bulk and as a function of distance from the solute molecules. Reverse non-equilibrium molecular dynamics (RNEMD) simulations were used to determine interfacial widths, friction coefficients ($\kappa$) with ice, and solution phase viscosities ($\eta$). Ionic solutes were found to reduce orientational and translational ordering near the ice interfaces. However, in bulk liquids, we find a correlation between orientational ordering and the statistics of water hydrogen bonds -- a donor-acceptor imbalance in water has the greatest impact on ordering in the bulk liquids. Although ionic solutions exhibited similar effects on the water structure, the effect on dynamics depends most directly on donor-acceptor imbalance. Solutes that are hydrogen bond acceptors were found to slow hydrogen bond lifetimes relative to hydrogen bond donors. We also observed a direct correlation between the liquid phase hydrogen-bond jump times and shear viscosity. Finally, of all the solutes studied, only DMSO and sodium formate exhibited increased friction at the ice-water interface.