四唑互变异构反应的密度泛函理论(DFT)研究

运用11种密度泛函理论方法对四唑互变异构反应进行了计算研究。结果表明,B3LYP-DFT法与从头算的优化几何和能量最为吻合;在6-31^*基组下B3LYP计算的IR频率与MP2/6-311G^*^*计算结果相差很小;用未经校正的B3LYP计算频率求得的产物(2H-四唑)的热力学性质与实测结果也完全一致;由此推荐B3LYP-DFT法适合于对四唑化合物作系统研究。

Theoretical study on tautomerization with density functional theory (DFT)

Nowadays density functional theory (DFT) methods have been very popular in investigating various chemical problems, due to the lower cost of computational time in dealing with electron correlation problem. However, the first thing one should do is to select the most suitable DFT method for the system and problem studied. Our recent studies reveal that electron correlation in tetrazoles is greater. To the best of our knowledge, no papers concerning investigations on tetrazoles using DFT approaches have been published. To select the appropriate DFT method for tetrazole, in this paper we employed various kinds of DFT methods on tautomerization of tetrazole. The results show that the optimized geometries and calculated energetic with hybrid DFT B3LYP at 6-31G* level are in best agreement with the high level ab initio' s results, In addition, The IR frequencies from B3LYP/6-31G* are very close to the corresponding frequencies obtained from MP2/6-311G* * . The calculated thermodynamic properties with the unsealed frequencies from B3LYP/6-31G* agree with the experimental ones excellently. The above facts show that hybrid B3LYP-DFT method is the first choice for investigating tetrazoles.