The structure and dynamics of solvation shells of the phosphate ion in deuterated water are studied by means of Born–Oppenheimer molecular dynamics simulation. The total number of molecules in the first and second solvation shells is found to be close to the effective hydration number reported experimentally. The OD bonds that are hydrogen bonded to the phosphate ion are found to be red shifted as compared to bulk water, which is consistent with experimental results. However, the two OD bonds of the same water molecule in the first hydration shell are found to be vibrationally distinct, which can be attributed to different strengths of the ion–water and water–water hydrogen bonds near the ion. Also, the hydrogen bonds formed by the second solvation shell OD bonds are somewhat stronger than the bulk. This finding shows a long ranged effect of the phosphate ion on water and also gives insights into the water structure making property of this anion. The dynamics of water in the first solvation shell is found to be significantly slower than that of the bulk. We have investigated the origin of the orientational slowing down of the first solvation shell water molecules and made connections to similar results observed experimentally.

中文翻译：

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水中磷酸根离子的从头算分子动力学模拟：对溶剂壳结构，动力学和同溶活性的认识

通过Born–Oppenheimer分子动力学模拟研究了氘化水中磷酸根离子的溶剂化壳的结构和动力学。发现第一和第二溶剂化壳中的分子总数接近于实验报道的有效水合数。与大量水相比，发现氢键合到磷酸根离子上的OD键发生了红移，这与实验结果一致。但是，发现在第一个水合壳中，同一水分子的两个OD键在振动上是不同的，这可以归因于离子附近的离子-水和水-水氢键强度不同。而且，由第二溶剂化壳OD键形成的氢键比本体键强一些。这一发现显示了磷酸根离子对水的远距离影响，并且还提供了对该阴离子的水结构制造特性的见解。发现第一溶剂化壳中的水动力学明显慢于本体中的水动力学。我们已经研究了第一个溶剂化壳水分子定向减慢的起源，并与实验观察到的类似结果建立了联系。