摘要
构建水滑石(LDHs-Cl-yH2O)周期性计算模型,选用密度泛函理论-赝势平面波法对模型进行几何全优化,从结构参数、Mulliken电荷布居、态密度(DOS)、能量等角度研究层间Cl-和水分子的分布形态以及与LDHs层板间的超分子作用.计算结果表明,LDHs-Cl主客体间存在着较强的超分子作用,主要包括静电和氢键作用.LDHs-Cl层间引入水分子后,随着水分子数的增加,层间距逐渐增大后趋于平衡.水合过程中氢键作用比静电作用更占优势,layer-water型氢键要略强于anoin-water型氢键.当y=1,2时,Cl-与水分子所在平面以平行层板的方式存在于LDHs层板间,并且与两层板的距离基本相等;当y=3,4时,Cl-与水分子则以偏向某一层的方式随机地存在于LDHs层板间.随着层间水分子增加,LDHs-Cl-yH2O由离子型晶体向分子型晶体转化,LDHs-Cl的水合具有饱和量.
A periodical interaction model of LDHs-Cl^-yH2O has been proposed. The geometry optimization and energy of the layered double hydroxides （LDHs） were calculated using CASTEP/LDA method at the CA-PZ level. The distribution of H2O in the interlayer and the super-molecular interaction between host layer and guest anion have been investigated by analyzing the geometric parameters, charge population, energy, and density of state （DOS）. The results showed that there was a strong super-molecular interaction between the host layer and the guest anion Cl^-. In the system of LDHs-Cl^-yH2O, the interlayer distance increased gradually then tended to invariableness. And in the process of hydration of LDHs-Cl, hydrogen bonding was superior to electrostatic interaction, and layer-water type hydrogen bonding was a little stronger than anion-water type hydrogen bonding between H2O and the rest of the structure. When y was I or 2, Cl^- and the plane of water molecule were parallel to the layer; while y was 3 or 4, distribution of Cl^- and water was random. Moreover, the LDHs-CI-yH2O would change from ionic crystal to molecular crystal with the increase of number of water molecule. The hydration of LDHs-Cl would achieve a definite saturation state.
出处
《物理化学学报》
SCIE
CAS
CSCD
北大核心
2008年第4期601-606,共6页
Acta Physico-Chimica Sinica
基金
浙江省自然科学基金(Y406069)资助项目
关键词
水滑石
超分子作用
水合能
密度泛函理论
Layered double hydroxides （LDHs）
Super-molecular interaction
Hydration energy
Densityfunction theory
