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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Ab Initio Investigation of Dissolution Mechanisms in Aiuminosilicate Minerals
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Ab Initio Investigation of Dissolution Mechanisms in Aiuminosilicate Minerals

机译：从头开始研究铝硅酸盐矿物中的溶解机理

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摘要

The reactions of aiuminosilicate clusters with water are investigated using ab initio calculations. There are several reaction sites on a mineral surface, and, in the case of aluminosilicates, the dissolution chemistry is dictated by chemically distinct surface termination sites: Al and Si. Environmental factors such as pH determine the protonation state and configuration around these terminal sites. The dissolution mechanisms for Al- and Si-terminated sites in protonated, neutral, and deprotonated states are determined using density functional theory calculations. In all protonation states, Si are tetra-coordinated; however, the ability of Al to exist in tetra-, penta-, and hexa-coordination states makes the dissolution mechanisms for the two types of terminal sites fundamentally different. The calculated barrier heights for Al-terminated sites are predicted to be lower than those for Si-terminated sites, a trend that has been observed in experimental studies. The sensitivity of the calculations on the choice of density functionals and basis sets is tested using three functionals: B3LYP, PBE1PBE, and M05-2X, in combination with the 6-311+G(d,p) and MG3S basis sets. For all these calculations, the geometries of the stationary points along the reaction path and the barrier heights are presented.
机译：从头算计算研究了硅铝酸盐团簇与水的反应。矿物表面上有多个反应位点，对于铝硅酸盐而言，溶解化学取决于化学上不同的表面终止位点：Al和Si。 pH等环境因素决定了这些末端位点附近的质子化状态和构型。使用密度泛函理论计算确定质子化，中性和去质子化状态下铝和硅末端位点的溶解机理。在所有质子化状态下，Si都是四配位的。但是，Al以四，五和六配位态存在的能力使两种末端位点的溶解机理根本不同。预计铝端接位点的计算出的势垒高度低于硅端接位点的势垒高度，这一趋势已在实验研究中观察到。使用三种功能（B3LYP，PBE1PBE和M05-2X，结合6-311 + G（d，p）和MG3S基础集）测试了对密度泛函和基集选择的计算敏感性。对于所有这些计算，都显示了沿反应路径的固定点的几何形状和势垒高度。

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