蒙脱石晶体结构构型及其XRD、IR的分子模拟

Molecular Simulations of Crystal Structure Conformation,X-Ray Diffraction and Infra-Red Spectrum in Montmorillonites

利用Cerius2软件分别构建了15种含有0～96个水分子的Li-、Na-、K-蒙脱石超晶格模型。分析了模型结构中的键长和键角,运用分子力场方法—UFF力场构型优化得到蒙脱石的最优构型及其总能量等参数,在此基础上计算了3种蒙脱石含有32、64和96个水分子时晶体结构的X射线衍射(XRD)和红外吸收光谱(IR)。结果表明,蒙脱石结构模型中键长和键角等参数说明其结构具有合理性;当蒙脱石的结构达到能量最小构型时,体系的总能量随着水含量的增加而降低;XRD的模拟结果和实验结果相一致;IR的模拟结果与实验结果有所偏离,可能是由选取的分子力场和分子位能模型所致。

A series of 15 superlattice models of Li-,Na-,and K-montmorillonites containing 0 to 96 water molecules were established respectively by using Cerius^2 software.The optimum conformation,total energy of montmorillonites were obtained by using molecular force field method（UFF）.On the basis of the minimum-energy,X-ray diffraction（XRD） and Infra-red spectrum（IR）,three kinds of montmorillonites with 32,64 and 96 molecules were calculated,respectively.Parameters of bond lengths and bond angles in the structures of montmorillonites illustrated that these models were feasible.When these structures of montmorillonites were minimum-energy conformations,the total energy of the system was decreased with water content.The simulated results of XRD were in agreement with experiments.While the simulated results of IR spectrum were deviated from experimental results,which was caused possibly by the type of force field and potential function.