水分子在高岭石(001)面吸附的密度泛函计算

Density Functional Calculations of Adsorption of Water Molecules on Kaolinite (001) Surface

为研究高岭石(001)面与水分子的相互作用机理,用Material studio 8.0构建了高岭石(001)面的晶体模型,使用GGA-PBE优化高岭石(001)面,分别计算(001)面和含有1、2、4个水分子的分子团吸附构型和平均结合能。结果表明,随着水分子数量的增加,结合能绝对值从35.87 kJ/mol增加到53.94 kJ/mol,复合体系稳定性增加。通过静电势分析可知,高岭石表面主要是负静电势区域略大于正静电势区域。当水分子数量由1个增加到4个时,静电势绝对值较大(>188.18 kJ/mol)的面积由7.99%增加到8.49%,整体静电势水平提高,有利于后续水分子吸附。运用RDG函数,展示了高岭石和水分子之间的弱相互作用,结果表明高岭石和水分子主要通过氢键方式结合。由AIM分析的结果可知,高岭石-水的氢键键能弱于水-水的氢键,当水分子数量增加时,高岭石-水氢键键能会进一步减弱。

In order to study the interaction mechanism between kaolinite(001)surface and water molecules,the crystal model of kaolinite(001)surface was constructed with Material studio 8.0,and the kaolinite(001)surface was optimized by GGA-PBE.The adsorption configurations and average binding energies of(001)surface and molecular groups containing 1,2 and 4 water molecules were calculated respectively.The results show that as the number of water molecules increases,the binding energy increases from 35.87 kJ/mol tO53.94 kJ/mol,and the stability of the composite system increases.According to the electrostatic potential analysis,the negative electrostatic potential area is slightly larger than the positive electrostatic potential area on the surface of kaolinite.When the number of water molecules increases from 1 to 4,the area of larger absolute value(>188.18 kJ/mol)of electrostatic potential increases from 7.99%to 8.49%,and the overall electrostatic potential level increases,which is conducive to the subsequent adsorption of water molecules.Using the RDG function,the weak interaction between kaolinite and water molecules was demonstrated.The results show that kaolinite and water molecules are mainly bonded by hydrogen bonding.From the results of AIM analysis,it can be seen that the hydrogen bonds of kaolinite-water is weaker than the hydrogen bonds of water-water.When the number of water molecules increases,the kaolinite-water hydrogen bond energy is further weakened.