Computational Science, Department of Chemistry and Applied Biosciences, ETHZ Zurich USI-Campus, Via Giuseppe Buffi 13 C-6900 Lugano, Switzerland.
J Phys Chem B. 2009 Aug 27;113(34):11680-7. doi: 10.1021/jp902606x.
The precipitation of calcium carbonate in water has been examined using a combination of molecular dynamics and umbrella sampling. During 20 ns molecular dynamics trajectories at elevated calcium carbonate concentrations, amorphous particles are observed to form and appear to be composed of misaligned domains of vaterite and aragonite. The addition of further calcium ions to these clusters is found to be energetically favorable and virtually barrierless. By contrast, there is a large barrier to the addition of calcium to small calcite crystals. Thus, even though calcite nanocrystals are stable in solution, at high supersaturations, particles of amorphous material form because this material grows much faster than ordered calcite nanocrystals.
使用分子动力学和伞形采样的组合研究了水中碳酸钙的沉淀。在升高的碳酸钙浓度下进行的 20 ns 分子动力学轨迹中，观察到无定形颗粒形成，并且似乎由文石和方解石的未对准域组成。发现向这些簇中添加更多的钙离子在能量上是有利的，几乎没有障碍。相比之下，向小方解石晶体添加钙的障碍很大。因此，尽管方解石纳米晶体在溶液中稳定，但在高过饱和度下，无定形材料的颗粒会形成，因为这种材料的生长速度比有序的方解石纳米晶体快得多。
