A molecular dynamics study of the swelling patterns of Na/Cs-montmorillonites and the hydration of interlayer cations

We report on a molecular dynamics study of the swelling patterns of an Na-rich/Cs-poor montomorillonite and a Csmontomorillonite.The recently developed CLAYFF force field is used to predict the basal spacing as a function of the water content in the interlayer.The simulations reproduce the swelling patterns of the Na and Cs-montomorillonite,suggesting a mechanism of its hydration different from that of the montomorillonite.In addition,we find that the differences in size and hydration energy of Na and Cs ions have strong implications for the structure and the internal energy of interlayer water.In particular,our results indicate that the hydrate difference in the presence of coexistent Na and Cs has a larger influence on the behavior of a clay-water system.For Na-rich/Cs-poor montomorillonite,the hydration energy values of Na ions and water molecules each have a dramatic increase compared with those in Na-montomorillonite on the interlayer spacing,and the hydration energy values of Cs ions and water molecules decrease somewhat compared with those in Cs-montomorillonite.     

Molecular dynamics study of swelling patterns of Na/Cs-montmorillonites and hydration of interlayer cations

We report on a molecular dynamics study of swelling patterns of an Na-rich/Cs-poor montomorillonite and a Cs-montomorillonite. The recently developed CLAYFF force field is used to predict the basal spacing as a function of the water content in the interlayer. The simulations reproduce the swelling patterns of the Na and Cs-montomorillonite, suggesting a mechanism of its hydration different from that of the montomorillonite. In the meanwhile, we find that the differences in size and hydration energy of Na and Cs ions have strong implications for the structure and the internal energy of interlayer water. In particular, our results indicate that the hydrate difference in the presence of coexistent Na and Cs has a larger influence on the behavior of clay-water system. For Na-rich/Cs-poor montomorillonite, the hydration energy values of Na ions and water molecules each have a dramatic increase compared with those in Na-montomorillonite on the interlayer spacing, and the hydration energy values of Cs ions and water molecules decrease somewhat compared with those in Cs-montomorillonite.     

重费米子超导PuMGa5(M=Co,Rh)结构、电子和热力学性质的第一性原理研究

基于第一性原理的PBEsol+U方法研究PuCoGa5和PuRhGa5的晶体结构、弹性、电子性质、声子谱以及热力学性质.PBEsol+U方法考虑Pu-5f的库伦排斥作用U和Hund交换相关作用J.计算结果表明,PuCoGa5和PuRhGa5在PBEsol+U方法下的基态性质(包括晶格参数和原子占位)与实验数据吻合较好,...