Derivation of an Accurate Force-Field for Simulating the Growth of Calcium Carbonate from Aqueous Solution: A New Model for the Calcite-Water Interface
Derivation of an Accurate Force-Field for Simulating the Growth of Calcium Carbonate from Aqueous Solution: A New Model for the Calcite-Water Interface
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DOI：
10.1021/jp910977a
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发表时间：
2010-04-08
影响因子：
3.7
通讯作者：
Rodger, P. Mark
中科院分区：
文献类型：
--
作者：
Raiteri, Paolo;Gale, Julian D.;Rodger, P. Mark
现有的碳酸钙-水体系的力场模型的性能已被严格评估，特别是参考热力学后果。结果表明，目前所有可用的参数都不能描述方解石-文石的相变，并且钙离子的溶剂化自由能也有相当大的误差，导致方解石的溶解焓描述很差。一种基于刚性碳酸盐离子的新力场已经被开发出来，它纠正了这些缺陷，并在分子动力学模拟中准确地描述了碳酸钙水溶液体系的热力学。这个新模型不仅导致了方解石（10 (1)over bar4）表面与水接触的性质的定量变化，而且还导致了显著的定性差异。通过这个更精确的模型，我们发现钙离子不吸附在方解石的原始基面上，而碳酸盐离子仅弱结合。研究发现，只有当阴离子作为溶剂与下表面分离时，碳酸盐才会在表面上扩散，并且有同样的再吸收或迁移到散装液体中的趋势。
The performance of existing force-field models for the calcium carbonate - water system has been critically assessed with particular reference to the thermodynamic consequences. It is demonstrated that all currently available parametrizations fail to describe the calcite-aragonite phase transition, and the free energies of solvation for the calcium cation are also considerably in error leading to a poor description of the dissolution enthalpy for calcite. A new force-field, based on rigid carbonate ions, has been developed that corrects these deficiencies and accurately describes the thermodynamics of the aqueous calcium carbonate system within molecular dynamics simulations. Not only does this new model lead to quantitative changes in the properties of the calcite (10 (1) over bar4) surface in contact with water, but also significant qualitative differences. With this more accurate model it is found that calcium ions do not adsorb at the pristine basal plane of calcite, while carbonate ions only weakly bind. Carbonate diffusion across the surface is found to occur only when the anion is solvent separated from the underlying surface, with there being an equal tendency to readsorb or migrate into the bulk liquid.