用高精度计算方法 CBS-4M,CBS-Q和CBS-QB3评估了26种单杂环分子的C-H键解离焓的实验值.结果表明,CBS-QB3方法最好,MD、MAD及RMSE分别为9.3、9.3和11.1 k J/mol.理论值与实验值的线性相关方程为y=0.928x+21.3,相关系数平方R2达0.980.通...用高精度计算方法 CBS-4M,CBS-Q和CBS-QB3评估了26种单杂环分子的C-H键解离焓的实验值.结果表明,CBS-QB3方法最好,MD、MAD及RMSE分别为9.3、9.3和11.1 k J/mol.理论值与实验值的线性相关方程为y=0.928x+21.3,相关系数平方R2达0.980.通过自然键轨道分析后发现,杂原子的电负性使得五元杂环的自然电荷分布发生变化.展开更多
The density functional theory （DFT） is the most popular method for evaluating bond dis- sociation enthalpies （BDEs） of most molecules. Thus, we are committed to looking for alternative methods that can balance the...The density functional theory （DFT） is the most popular method for evaluating bond dis- sociation enthalpies （BDEs） of most molecules. Thus, we are committed to looking for alternative methods that can balance the computational cost and higher precision to the best for large systems. The performance of DFT, double-hybrid DFT, and high-level com- posite methods are examined. The tested sets contain monocyclic and polycyclic aromatic molecules, branched hydrocarbons, small inorganic molecules, etc. The results show that the mPW2PLYP and G4MP2 methods achieve reasonable agreement with the benchmark val- ues for most tested molecules, and the mean absolute deviations are 2.43 and 1.96 kcal/mol after excluding the BDEs of branched hydrocarbons. We recommend the G4MP2 is the most appropriate method for small systems （atoms number≤20）; the double-hybrid DFT methods are advised for large aromatic molecules in medium size （20≤atoms number≤50）, and the double-hybrid DFT methods with empirical dispersion correction are recommended for long-chain and branched hydrocarbons in the same size scope; the DFT methods are ad- vised to apply for large systems （atoms number〉50）, and the M06-2X and B3P86 methods are also favorable. Moreover, the differences of optimized geometry of different methods are discussed and the effects of basis sets for various methods are investigated.展开更多
The formation and breaking of Ni-L （L=N-heterocyclic carbene, tertiary phosphine etc.） bond is involved in many Ni-catalyzed/mediated reactions. The accurate prediction of Ni-L bond dissociation enthalpies （BDEs） ...The formation and breaking of Ni-L （L=N-heterocyclic carbene, tertiary phosphine etc.） bond is involved in many Ni-catalyzed/mediated reactions. The accurate prediction of Ni-L bond dissociation enthalpies （BDEs） is potentially important to understand these Ni-complex involving reactions. We assess the accuracy of diffierent DFT functionals （such as B3LYP, M06, MPWB1K, etc.） and diffierent basis sets, including both effective core potentials for Ni and the all electron basis sets for all other atoms in predicting the Ni-L BDE values reported recently by Nolan et al. [J. Am. Chem. Soc. 125, 10490 （2003） and Organometallics 27, 3181 （2008）]. It is found that the MPWB1K/LanL2DZ：6-31＋G（d,p）//MPWB1K/LanL2DZ：6-31G（d） method gives the best correlations with the experimental results. Meanwhile, the solvent effect calculations （with CPCM, PCM, and SMD models） indicate that both CPCM and PCM perform well.展开更多
文摘用高精度计算方法 CBS-4M,CBS-Q和CBS-QB3评估了26种单杂环分子的C-H键解离焓的实验值.结果表明,CBS-QB3方法最好,MD、MAD及RMSE分别为9.3、9.3和11.1 k J/mol.理论值与实验值的线性相关方程为y=0.928x+21.3,相关系数平方R2达0.980.通过自然键轨道分析后发现,杂原子的电负性使得五元杂环的自然电荷分布发生变化.
基金the Guangdong Provincial Natural Science Foundation of China(003062) Guangdong Provincial Science and Technology Planning Projects of China(2003C20406)
文摘The density functional theory （DFT） is the most popular method for evaluating bond dis- sociation enthalpies （BDEs） of most molecules. Thus, we are committed to looking for alternative methods that can balance the computational cost and higher precision to the best for large systems. The performance of DFT, double-hybrid DFT, and high-level com- posite methods are examined. The tested sets contain monocyclic and polycyclic aromatic molecules, branched hydrocarbons, small inorganic molecules, etc. The results show that the mPW2PLYP and G4MP2 methods achieve reasonable agreement with the benchmark val- ues for most tested molecules, and the mean absolute deviations are 2.43 and 1.96 kcal/mol after excluding the BDEs of branched hydrocarbons. We recommend the G4MP2 is the most appropriate method for small systems （atoms number≤20）; the double-hybrid DFT methods are advised for large aromatic molecules in medium size （20≤atoms number≤50）, and the double-hybrid DFT methods with empirical dispersion correction are recommended for long-chain and branched hydrocarbons in the same size scope; the DFT methods are ad- vised to apply for large systems （atoms number〉50）, and the M06-2X and B3P86 methods are also favorable. Moreover, the differences of optimized geometry of different methods are discussed and the effects of basis sets for various methods are investigated.
基金This work was supported by the National Nature Science Foundation of China （No.21325208, No.21172209, No.21202006, No.21361140372）, the Anhui Provincial Natural Science Foundation （No.1308085QB38）, the Specialized Research Fund for the Doctoral Program of Higher Education （No.20123402110051）, the Financial Resources Federal Credit Union （No.WK2060190025, No.FRF-TP-13-023A）, the Science Foundation of the Chinese Academy of Sciences （No.JCX2-EW-J02）, the Fok Ying Tung Education Foundation, the ChinaGrid project funded by MOE of China and the supercom- puter center of Shanghai and USTC.
文摘The formation and breaking of Ni-L （L=N-heterocyclic carbene, tertiary phosphine etc.） bond is involved in many Ni-catalyzed/mediated reactions. The accurate prediction of Ni-L bond dissociation enthalpies （BDEs） is potentially important to understand these Ni-complex involving reactions. We assess the accuracy of diffierent DFT functionals （such as B3LYP, M06, MPWB1K, etc.） and diffierent basis sets, including both effective core potentials for Ni and the all electron basis sets for all other atoms in predicting the Ni-L BDE values reported recently by Nolan et al. [J. Am. Chem. Soc. 125, 10490 （2003） and Organometallics 27, 3181 （2008）]. It is found that the MPWB1K/LanL2DZ：6-31＋G（d,p）//MPWB1K/LanL2DZ：6-31G（d） method gives the best correlations with the experimental results. Meanwhile, the solvent effect calculations （with CPCM, PCM, and SMD models） indicate that both CPCM and PCM perform well.
