Ockwig Nathan W, Cygan Randall T, Criscenti Louise J, Nenoff Tina M
Geochemistry Department, Sandia National Laboratories, P.O. Box 5800, Albuquerque, NM 87185, USA.
Phys Chem Chem Phys. 2008 Feb 14;10(6):800-7. doi: 10.1039/b711949f. Epub 2007 Dec 10.
The complete periodic series of alkali and alkaline earth cation variants (Li(+), Na(+), K(+), Rb(+), Cs(+), Mg(2+), Ca(2+), Sr(2+), and Ba(2+)) of clinoptilolite (Si : Al=5) and heulandite (Si : Al=3.5) aluminosilicate zeolites are examined by large-scale molecular dynamics utilizing a flexible SPC water and aluminosilicate force field. Calculated hydration enthalpies, radial distribution functions, and ion coordination environments are used to describe the energetic and structural components of extra-framework species while power spectra are used to examine the intermolecular dynamics. These data are correlated to evaluate the impact of ion-zeolite, ion-water, and water-zeolite interactions on the behavior of nanoconfined water. Analysis of the correlated data clearly indicates that the charge density of extra-framework cations appears to have the greatest influence on librational motions, while the anionic charge of the framework (i.e. Si:Al ratios) has a lesser impact.
利用灵活的SPC水和硅铝酸盐力场，通过大规模分子动力学研究了斜发沸石（Si:Al = 5）和片沸石（Si:Al = 3.5）硅铝酸盐沸石的碱金属和碱土金属阳离子变体（Li(+)、Na(+)、K(+)、Rb(+)、Cs(+)、Mg(2+)、Ca(2+)、Sr(2+)和Ba(2+)）的完整周期系列。计算得到的水合焓、径向分布函数和离子配位环境用于描述骨架外物种的能量和结构成分，而功率谱用于研究分子间动力学。这些数据相互关联，以评估离子-沸石、离子-水和水-沸石相互作用对纳米受限水行为的影响。对相关数据的分析清楚地表明，骨架外阳离子的电荷密度似乎对振动运动影响最大，而骨架的阴离子电荷（即Si:Al比）影响较小。
