摘要
设计不同的超分子计算模型簇Z…X(Z=2TNa([H3SiOAlH3]-Na+),3TNa([H3SiOAl(H)2OSiH3]-Na+)和4TNa([H3SiOAl(H)2OSi(H)2OSiH3]-Na+),X=C2H4、N2和CH4),模拟计算C2H4、N2和CH4与沸石模型簇的相互作用.在HF/6-31G水平上对Z、X和复合物Z…X进行几何全优化计算得到优化构型,经MP2/6-31G*电子相关能校正和基组重叠误差(BSSE)校正以获得相互作用能.结果表明,对于一指定X,随Z尺寸增大,复合物Z…X的相互作用能减小;对于一指定Z,复合物Z…X的相互作用能由大到小顺序为Z…C2H4>Z…N2 Z…CH4.分子间相互作用的能量分解分析显示,静电能在Z…X相互作用能量中占主导地位,电荷转移能在Z…C2H4复合物体系中居第2位,而极化能在Z…N2和Z…CH4复合物体系中居第2位.
The interactions of C2H4、N2 and CH4 lecular orbital calculations on different models with zeolite cluster models have been investigated by ab initio molecular orbital calculations on different models Z （ where Z = 2TNa （ [ H3SiOAlH3 ] ^- Na^＋ ） , 3TNa （ [ H3SiOAl （ S）2OSiS3 ]^- Na^＋ ）, and 4TNa（ [ H3 SiOAl （ S）2OSi （ H）2OSiH3 ]^- Na^＋ ） to be used to represent a fragment of a zeolite. Geometry optimization of Z ,X（ X = C2H4, N2 and CH4 ）and Z…X complexes are performed using HF method at 6-31 G level. After geometry optimization, single-point calculations are made with MP2/6 - 31 G ＊. All the interac-tion energies have been corrected by the basis set superposition error（BSSE） with counterpoise methods. The most characteristic geometrical properties of the complex are the lengthening of the contacting O…Na ^＋ distances, and for a given Z,the distances between bridging O and Na^＋ always lengthen in the order Z,..C2H4 〉 Z...N2 〉 Z…CH4 with respect to the monomers Z. It is essential to take into account the effects of the cluster models size. The theoretical calculations reveal that for a given X, the interaction energies of complex Z…X increased with the increase of Z size,and for a given Z,the interaction energies of complex Z…X vary as Z…CH4〉〉Z…N2 〉 Z…C2H4. The agree-ment of the calculated and observed results is as good as that seen for the adsorption order of C2H4, N2 and CH4 on the zeolite. The results of molecular interaction energy decomposition analysis show that the electrostatic and charge-transfer interactions play an essential role in stabilizing the Z…C2H4 complex, and the electrostatic and polarization interactions play an essential role in stabilizing the Z…N2 and Z…CH4 complex. The present results further suggest that Na^＋ takes an important role as the intermediate.
出处
《商丘师范学院学报》
CAS
2007年第3期74-77,共4页
Journal of Shangqiu Normal University
