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首页> 外文期刊>The Journal of Chemical Physics >Calibration and comparison of the Gaussian-2, complete basis set, and density functional methods for computational thermochemistry
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Calibration and comparison of the Gaussian-2, complete basis set, and density functional methods for computational thermochemistry

机译：高斯2的校准和比较，完整的基集以及用于计算热化学的密度泛函方法

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We have reexamined several high-accuracy Gaussian-2, complete basis set and density functional methods for computational thermochemistry tin order of increasing speed): G2, G2(MP2), CBS-Q, G2(MP2,SVP), CBS-q, CBS-4, and B3LYP/6-311 + G(3 df,2p). We have employed Delta(f)H(298)(0) for the "extended G2 neutral test set" for this comparison. Several errors in previous studies have been corrected and experimental spin-orbit interactions have been included in all calculated atomic energies. The mean absolute deviations from experiment are 1.43, 1.76, 1.19, 1.64, 2.34, 2.66, and 3.43 kcal/mol, respectively. The maximum deviations from experiment are 10.6, 8.8, 8.1, 9.4, 11.4, 12.9, and 24.1 kcal/mol respectively. The species responsible for these maximum errors are in order: SiF4, SiF4, Cl2C=CCl2, F2C=CF2, ClF3, ClF3, and SiCl4. All seven methods have relatively large errors for bonds to halogens, but these errors are sufficiently systematic to benefit from empirical corrections. After a discussion of ill conditioning in the "bond separation reaction" implementation of isodesmic reactions, we determine "isodesmic bond additivity corrections" (BACs) for several types of bonds by least-squares fits to the heats of formation for 76 organic species with up to ten carbons and a variety of heteroatoms. The mean absolute deviations are reduced from 1.49, 1.93, 1.22, 1.53, 2.28, 3.09, and 3.45 kcal/mol to 0.55, 0.57, 0.77, 0.63, 1.03, 0.98, and 1.16 kcal/mol. The maximum errors are reduced to about 3 kcal/mol for all but the DFT method (4.2 kcal/mol). The BACs are especially useful for larger molecules with many similar bonds. For example, the CBS-Q error for Cl2C=CCl2 is reduced from 8.1 to 3.0 kcal/mol and the CBS-4 errors for benzene and naphthalene are reduced from 10.5 and 17.5 to 2.1 and 1.6 kcal/mol, respectively. (C) 1998 American Institute of Physics. [S0021-9606(98)3 1048-X]. [References: 26]
机译：我们已经重新审查了几种高精度Gaussian-2，完整的基集和密度泛函方法，以计算速度递增的热化学顺序）：G2，G2（MP2），CBS-Q，G2（MP2，SVP），CBS-q， CBS-4和B3LYP / 6-311 + G（3 df，2p）。为了进行比较，我们将Delta（f）H（298）（0）用于“扩展的G2中性测试仪”。先前研究中的一些错误已得到纠正，并且实验自旋轨道相互作用已包含在所有计算出的原子能中。与实验的平均绝对偏差分别为1.43、1.76、1.19、1.64、2.34、2.66和3.43 kcal / mol。与实验的最大偏差分别为10.6、8.8、8.1、9.4、11.4、12.9和24.1 kcal / mol。造成这些最大误差的物质依次为：SiF4，SiF4，Cl2C = CCl2，F2C = CF2，ClF3，ClF3和SiCl4。所有七个方法对于与卤素的键都有相对较大的误差，但是这些误差足够系统化，可以从经验校正中受益。在讨论等离子反应的“键分离反应”实施中的不良条件后，我们确定了几种键的“等键键加性校正”（BAC），最小二乘拟合了76种有机物的形成热。十个碳原子和各种杂原子平均绝对偏差从1.49、1.93、1.22、1.53、2.28、3.09和3.45 kcal / mol降低到0.55、0.57、0.77、0.63、1.03、0.98和1.16 kcal / mol。除DFT方法外，所有方法的最大误差均降至约3 kcal / mol（4.2 kcal / mol）。 BAC对于具有许多相似键的较大分子特别有用。例如，Cl2C = CCl2的CBS-Q误差从8.1降低到3.0 kcal / mol，苯和萘的CBS-4误差从10.5和17.5降低到2.1和1.6 kcal / mol。 （C）1998美国物理研究所。 [S0021-9606（98）3 1048-X]。 [参考：26]

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