中文摘要：

在B3LYP/6-311＋＋G（3df,2pd）水平上全优化得到了三甲基铝双聚体（d-TMA）的C2h和C2v两种构型和单体的C3h结构.着重用完全基组方法CBS-4M模拟计算了TMA气相平衡中各物种在1.01×105 Pa和300～550 K范围内的热力学函数值.通过考察d-TMA三线态构型和异裂反应对系统熵值的影响,准确计算了d-TMA离解反应的△rHm和△rSm.以lnKd对1/T作图,两者之间具有很好的线性关系：lnKd=-9624.4363/T＋20.2303,相关系数R2=1.0000,与前人实验结果相当一致.在此基础上提出了新的d-TMA气相离解-缔合反应机理.

英文摘要：

Both the C2h and C2u configurations of trimethylaluminum dimer （d-TMA） and the C3h structure of monomer were obtained by full optimization at B3LYP/6-311＋＋G（3df, 2pd） level. With Complete Basis Set method CBS-4M as emphasis, the thermodynamic function values of each species of TMA in gas-phase equilibrium at 1.01× 10^5 Pa and in the range of 300 -550 K were calculated by simulation. Through the consideration of the triplet-state configuration of d-TMA and the effect of heterolytic reaction on system entropy value, △rHm and △rSm of the dissociation reaction of d-TMA were accurately calculated at the same time. The plot of 1nKd vs 1/T had a perfectly linear relation： lnKd=-9624.4363/T＋20.2303, and the correlation coefficient R2=1.0000, which agreed quite well with the predecessors＇ experimental results. Based upon these findings, a new dissociation-association reaction mechanism of d-TMA in gas phase was proposed.