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采用Gaussian 03程序中的密度泛函理论(DFT)方法,在BHandHLYP/6-311G~(**)水平上对135个多氯10-氧吩噁噻系列化合物(PCPTO)进行了全优化和振动分析计算,得到了各分子在298.15 K, 1.013×10~5 Pa标准状态下的热力学参数.设计等键反应,计算了PCPTO系列化合物的标准生成热(△_fG~(⊙))和标准生成自由能(△_fG~(⊙)),同时研究了这些参数与氯原子的取代位置及取代数目(NPCS)之间的关系.结果表明:熵(S~(⊙)),△_fG~(⊙),△_fG~(⊙)与NPCS之间有很强的相关性(R2≥0.991).根据△_fG~(⊙)的相对大小,从理论上求得异构体的相对稳定性.以Gaussian 03程序的输出文件为基础,采用统计热力学程序计算了PCPTO化合物在200至1000 K的摩尔恒压热容(C_(p,m)),并用最小二乘法求得C_(p,m)与温度之间的相关方程,结果发现C_(p,m)与T,T~(-1)和T~(-2)之间有着很好的相关性(R~2= 1.000).“,”The thermodynamic properties of phenoxathiin 10-oxide (PTO) and 135 polychlorinated phenoxathiin 10-oxides (PCPTO) in the ideal gas state at 298.15 K and 1.013 × 10~5 Pa have been calculated at the BHandHLYP/6-311G~(**) level using Gaussian 03 program. The isodesmic reactions were designed to calculate standard enthalpy of formation (△_fH~(⊙)) and standard free energy of formation (△_fG~(⊙)) of PCPTO congeners. The relations of these thermodynamic parameters with the number and position of Cl atom substitution (Npcs) were discussed, and it was found that there exist high correlation between the thermodynamic parameters [entropy (S~(⊙)), △_fG~(⊙) and △_fG~(⊙)] and NPCSs (R2≥0.991). According to the relative magnitude of their △_fG~(⊙), the relative stability order of PCPTO congeners was theoretically proposed. Moreover, using a statistical thermodynamics calculation program based on Gaussian 03 output files, the values of molar heat capacity at constant pressure (C_(p,m)) from 200 to 1000 K for PCPTO congeners were calculated, and the temperature dependence relation of them was obtained, which suggests that there are very good relationships between C_(p,m) and temperature (T, T~(-1) and T~(-2)) for almost all PCPTO congeners (R~2= 1.000).