用密度泛函理论 (DFT)和从头算 (abinitio)方法 ,在B3LYP/ 6 - 31G、B3LYP/ 6 - 31G 、B3LYP/ 6 - 311G 和MP2 / 6 - 31G 水平上全优化计算了 2 ,3,7,8-四氯苯并二英 (2 ,3,7,8-TCDD)的几何构型、电子结构和振动频率 ,并用校正后的频率计算了 2 98～ 15 0 0K的标准热力学函数 ,同时用半经验的PM3SCF -MO进行了同样的计算 ,计算结果与实验值及文献值较好地吻合 The density functional theory (DFT) and ab initio method were used to optimize the concentration of 2, 3, 3, 6, 7, Geometry, electronic structure and vibrational frequency of 7,8-tetrachlorobenzodioxin (2,3,7,8-TCDD) were calculated and the standard thermodynamic function of 2 98 ~ 15 0 0K was calculated with the corrected frequency , And the same calculation is made with semi-empirical PM3SCF-MO, the calculated results are in good agreement with the experimental values ​​and literature values