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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Accurate Benchmark Calculations on the Gas-Phase Basicities of Small Molecules
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Accurate Benchmark Calculations on the Gas-Phase Basicities of Small Molecules

机译：小分子气相碱度的准确基准计算

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摘要

Accurate benchmark calculations of gas-phase basicities of small molecules are presented and comparedwith available experimental results. The optimized geometries and thermochemical analyses were obtainedfrom MP2/aug-cc-pVTZ calculations. Two different ab initio electron-correlated methods MP2 and CCSD(T)were employed for subsequent gas-phase basicity calculations, and the single-point energies were extrapolatedto the complete basis set (CBS) limit. The overall accuracy for different ab initio methods is compared, andthe accuracy in descending order is CCSD(T)_CBS > CCSD(T)/aug-cc-pVDZ > (MP2/aug-cc-pVQZ MP2_CBS) > HF/aug-cc-pVQZ. The best root-mean-squared-error obtained was 1.0 kcal mol~(-1)at theCCSD(T)_CBS//MP2/aug-cc-pVTZ level for a test set of 41 molecules. Clearly, accurate calculations for theelectron correlation energy are important for the theoretical prediction of molecular gas-phase basicities.However, conformational effects were also found to be relevant in several instances when more complicatedmolecules were examined.
机译：提出了小分子气相碱度的准确基准计算，并与可用的实验结果进行了比较。通过MP2 / aug-cc-pVTZ计算获得了优化的几何形状和热化学分析。两种不同的从头算电子相关的方法MP2和CCSD（T）用于随后的气相碱度计算，并将单点能量外推到完全基集（CBS）极限。比较了不同从头算方法的整体精度，降序精度为CCSD（T）_CBS> CCSD（T）/ aug-cc-pVDZ>（MP2 / aug-cc-pVQZ MP2_CBS）> HF / aug-cc -pVQZ。对于41个分子的测试集，在CCSD（T）_CBS // MP2 / aug-cc-pVTZ水平下获得的最佳均方根误差为1.0 kcal mol〜（-1）。显然，准确地计算电子相关能对于分子气相碱度的理论预测很重要。然而，当研究更复杂的分子时，在许多情况下构象效应也很重要。

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