PDF(Pubmed)
Abstract：
BACKGROUND: From a nuclear spin prospective, water exists as para and ortho nuclear spin isomers (isotopomers). Spin interconversions in isolated molecules of water are forbidden, but many recent reports have shown them to happen in bulk, through dynamic proton exchanges happening between interconnected networks of a large array of water molecules. In this contribution, a possible explanation for an unexpected slow or delayed interconversion of ortho-para water in ice observed in an earlier reported experiment is provided. Using the results of quantum mechanical investigations, we have discussed the roles played by Bjerrum defects in the dynamic proton exchanges and ortho-para spin state interconversions. We guess that at the sites of the Bjerrum defects, there are possibilities of quantum entanglements of states, through pairwise interactions. Based on the perfectly correlated exchange happening via a replica transition state, we speculate that it can have significant influences on ortho-para interconversions of water. We also conjecture that the overall ortho-para interconversion is not a continuous process, rather can be imagined to be happening serendipitously, but within the boundary of the rules of quantum mechanics.
METHODS: All computations were performed with Gaussian 09 program. B3LYP/6-31++G(d,p) methodology was used to compute all the stationary points. Further energy corrections were computed using CCSD(T)/aug-cc-pVTZ methodology. Intrinsic reaction coordinate (IRC) path computations were carried out for the transition states.
METHODS: All computations were performed with Gaussian 09 program. B3LYP/6-31++G(d,p) methodology was used to compute all the stationary points. Further energy corrections were computed using CCSD(T)/aug-cc-pVTZ methodology. Intrinsic reaction coordinate (IRC) path computations were carried out for the transition states.
摘要：
背景：从核自旋的角度来看，水以对位和邻位核自旋异构体（同位素）的形式存在。禁止在分离的水分子中进行自旋相互转化，但是最近的许多报告表明它们是大量发生的，通过大量水分子互连网络之间发生的动态质子交换。在这一贡献中,提供了在较早报道的实验中观察到的冰中邻位水的意外缓慢或延迟的相互转化的可能解释。利用量子力学研究的结果，我们已经讨论了Bjerrum缺陷在动态质子交换和正对位自旋态相互转换中的作用。我们猜在Bjerrum缺陷的地点，有量子纠缠状态的可能性，通过成对互动。基于通过副本过渡状态发生的完全相关的交换，我们推测它可以对水的邻位相互转化产生重大影响。我们还推测，整体的邻位-对位相互转换不是一个连续的过程，可以想象是偶然发生的，但在量子力学规则的边界内。
方法:用高斯09程序进行所有计算。B3LYP/6-31++G(d,p)方法用于计算所有固定点。使用CCSD(T)/aug-cc-pVTZ方法计算进一步的能量校正。对过渡态进行了本征反应坐标（IRC）路径计算。
方法:用高斯09程序进行所有计算。B3LYP/6-31++G(d,p)方法用于计算所有固定点。使用CCSD(T)/aug-cc-pVTZ方法计算进一步的能量校正。对过渡态进行了本征反应坐标（IRC）路径计算。
