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采用密度泛函方法计算了水溶液中B(OH)3和B(OH)4-间硼同位素的平衡分馏参数。在模拟液相环境时,采用基于分子簇模型的“水滴”法,分别以6、12、18、24和30个水分子环绕兴趣分子的方式构建“水滴”。对纯水体系的计算结果显示该分馏参数在25?C时为1.031,与实验测定值吻合地非常理想。对不同个数水分子所形成的液相构型进行比较,发现在计算硼同位素的分馏时,12个水分子的“水滴”构型是比较经济和准确的建模方式。此外,我们还讨论了前人对该体系分馏计算中存在的不足,并提出了将分子簇模型扩展到碳酸盐矿物形成过程中硼同位素分馏研究的可能。
The equilibrium Fractionation parameters of boron isotope between B (OH) 3 and B (OH) 4 in aqueous solution were calculated by density functional theory. When simulating the liquid environment, “water droplet” was constructed based on the “water droplet” method based on the molecular cluster model, in which 6, 12, 18, 24 and 30 water molecules respectively surround the interested molecules. The calculated results for the pure water system show that the fractionation parameter is 1.031 at 25 ° C, which is in good agreement with the experimental data. Comparing the liquid phase configurations formed by different numbers of water molecules, we found that the “water droplet” configuration of 12 water molecules is an economical and accurate modeling method in the calculation of boron isotope fractionation. In addition, we also discuss the shortcomings of predecessors in the fractional calculation of the system and propose the possibility of extending the molecular cluster model to boron isotope fractionation in carbonate mineral formation.