摘要
用密度泛函离散变分计算方法 (DFT -DVM ) ,研究了高岭石、高岭石 -金和高岭石 -金 -硫系列 ,讨论了结构、化学键与稳定性之间的关系 .选用了不含金及金或金 -硫原子团位于不同方位的多个模型 .计算结果表明 ,金位于层状高岭石侧面的模型比金位于上、下面更为稳定 .在金位于层状高岭石侧面的情况下 ,金靠近铝的模型比金靠近铝空位更为稳定 ,高岭石 -金 -硫体系中的金-硫原子团比高岭石 -金体系中的金更容易被高岭石吸附 .模型间各原子的电荷分配 ,Au—O及Si—O键强度的差异都是影响稳定性的重要因素 .
The correlation among structure, chemical bond and stability of systems of kaolnite, kaolnite-Au and kaolnite-Au—S is studied using density function and discrete variation method (DFT-DVM). Several models are selected without Au and with Au or Au—S cluster in different directions and sites. The results show that the models with gold adsorbed to the edge of kaolinite basal layer contain pincerlike bond between gold and several oxygen atoms and the Au—O covalent bond is stronger, so these models are more stable than those with gold adsorbed above or under the basal layer. Models with gold on the edge can be divided into two types. The first type is models with gold near to [AlO 2(OH) 4], and the second type is models with gold near to the vacancy without aluminium. In the first type of models, the net charge of silicon is lower and that of gold is higher, so the ionic bond of Au—O is stronger and the charge distribution is favorable to increase the stability. Therefore, the edge surface of kaolinite, especially near to [AlO 2(OH) 4] octahedra, are more easily to adsorb gold than gold is adsorbed above or under the basal layer. Au—S is more easily adsorbed, or more easily adsorbed on the edge and near to [AlO 2(OH) 4] octahedra in kaolinite-Au—S than gold is adsorbed in kaolinite-Au system. The stability is much affected by the differences of the charge distribution, Au—O and Si—O bond strengths among the models .
出处
《分子科学学报》
CAS
CSCD
2000年第1期43-48,共6页
Journal of Molecular Science
基金
国家自然科学基金!资助项目 ( 4 980 2 0 0 3 )
关键词
高岭石
金
量子化学计算
硫
化学键
稳定性
kaolnite-gold
structure
stability
quantum chemistry calculation
