中文摘要：

采用密度泛函B3P86方法和6-311＋＋G（3df,3pf）基组,计算了在-0.05～0.05a.u.外偶极电场作用下,H2O,D2O,T2O,H2,D2,T2,O2的电子能量、核运动能量和熵值,在此基础上通过计算H2O（g）→H2（g）＋O2（g）、D2O（g）→D2（g）＋O2（g）、T2O（g）→T2（g）＋O2（g）的焓变ΔH、熵变ΔS、Gibbs函数变化ΔG,最后得到了H2O,D2O,T2O的可逆分解电压Er.计算结果表明,外偶极电场存在时,H2O,D2O,T2O的Gibbs自由能变ΔG和可逆分解电压Er都有明显的变化,当外偶极电场正方向增加时,其Gibbs自由能变ΔG和可逆分解电压Er均趋于线性增加;当外偶极电场负方向增加时,其Gibbs自由能变ΔG和可逆分解电压Er均趋于线性减小;在相同外偶极电场作用下,Gibbs自由能变ΔG和可逆分解电压Er随H2O,D2O,T2O依次增加.

英文摘要：

The electric energy,nuclear energy and entropy of H2O,D2O,T2O,H2,D2,T2,O2 were calcu-lated under the dipole electric field from -0.05 to 0.05 a.u.,employing B3P86 method of the density func-tional theory with basis sets 6-311＋＋G（3df,3pf）,by further calculating the enthalpy change ΔH,entropy change ΔS,Gibbs function change ΔG in the reaction of H2O（g）→H2（g）＋O2（g）,D2O（g）→D2（g）＋O2（g）,T2O（g）→T2（g）＋O2（g）,the reversible decomposition voltage Er of H2O,D2O,T2O were obtained. The re-sults show that the presence of dipole electric field will evidently influence the change of Gibbs free energy ΔG and the reversible decomposition voltage Er of H2O,D2O,T2O,for example,when the positive dipole electric field increases,the Gibbs free energy change ΔG and reversible decomposition voltage Er tend to a linear increase; but when the negative dipole electric field increases,the Gibbs free energy change ΔG and reversible decomposition voltage Er tend to a linear decrease,under the same dipole electric field,Gibbs free energy change ΔG and reversible decomposition voltage Er increase with the order of H2O,D2O,T2O.