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采用Politzer经验公式,运用密度泛函理论研究了升华焓的预估方法。基于在B3LYP/6–31G**水平上获得56种化合物稳定构型的基础上,运用Multiwfn软件对分子表面进行了定量分析。对比研究了采用Politzer系数和Rice系数对升华焓预估值的影响,结果表明,Politzer系数和Rice系数所造成的最大误差分别为46.1 kJ/mol和38.9 kJ/mol。为了缩小误差,根据34种化合物升华焓的实验值拟合出了一组新的系数(0.000 409(α),2.005 0(β),–2.82(γ)),并用来计算了22种含能化合物的升华焓。计算结果表明,该组新系数使计算值的最大误差为32.6 kJ/mol,标准偏差为13.8 kJ/mol。
Using Politzer empirical formula, the density functional theory is used to study the prediction method of sublimation enthalpy. Based on the stable configuration of 56 compounds obtained at B3LYP / 6-31G ** level, the molecular surface was quantitatively analyzed by Multiwfn software. The effects of using the Politzer coefficient and the Rice coefficient on the predicted sublimation enthalpy were compared. The results showed that the maximum errors caused by the Politzer coefficient and the Rice coefficient were 46.1 kJ / mol and 38.9 kJ / mol, respectively. In order to reduce the error, a new set of coefficients (0.000409 (α), 2.005 0 (β), -2.82 (γ)) were fitted based on the experimental values of the sublimation enthalpies of 34 compounds and used to calculate 22 new energies Sublimation enthalpy of the compound. The calculation results show that the maximum error of the new coefficient is 32.6 kJ / mol and the standard deviation is 13.8 kJ / mol.