Systematic investigation of modern quantum chemical methods to predict electronic circular dichroism spectra
Systematic investigation of modern quantum chemical methods to predict electronic circular dichroism spectra
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DOI：
10.1021/jp0275802
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发表时间：
2003-04-10
影响因子：
2.9
通讯作者：
Grimme, S
中科院分区：
文献类型：
--
作者：
Diedrich, C;Grimme, S
不同的量子化学方法预测实验电子圆二色性（CD）光谱的能力进行了严格的评估。考虑了两种基于密度泛函理论（TDDFT）或简化耦合聚类展开（CC2）的单参考时间依赖方法和两种多参考方法（MRMP2和DFT/MRCI）。这些方法应用于七个分子的测试套件，包括广泛的困难发色团（“现实生活”的例子）和三个模型系统- h2s2，扭曲乙烯和二甲基氯烷-其中精确的从头算MRCI参考数据用于比较。为了系统地研究“精确”交换混合的影响，使用BP86、B3-LYP和BH-LYP泛函进行了TDDFT计算。将时变Hartree-Fock （TDHF）方法作为函数中高频交换部分的“上限”。总的来说，大多数模拟光谱（TDHF除外）的精度足以确定手性分子的绝对构型。然而，描述弱扰动的固有非手性发色团和具有里德堡价混合的系统是相当困难的。此外，没有一种方法对测试套件中的所有分子都能可靠地执行，特别是，TDDFT结果对所使用的功能非常敏感。DFT/MRCI和CC2方法的综合性能最好。TDDFT方法应谨慎使用，特别是对于具有重要漫射或电荷转移状态的系统。在测试的三个功能中，B3-LYP似乎表现最好。在实践中，我们强烈建议同时应用不同的互补的单参考和多参考方法，这大大提高了理论预测的可靠性。
The ability of different quantum chemical methods to predict experimental electronic circular dichroism (CD) spectra is critically evaluated. Two single-reference, time-dependent approaches based either on density functional theory (TDDFT) or a simplified coupled-cluster expansion (CC2) and two multireference methods (MRMP2 and DFT/MRCI) are considered. The methods are applied to a test suite of seven molecules including a wide range of difficult chromophores ("real-life" examples) and to three model systems-H2S2, twisted ethylene, and dimethyloxirane-where accurate ab initio MRCI reference data are used for comparison. To investigate the effect of "exact" exchange mixing systematically, the TDDFT calculations were carried out with the BP86, B3-LYP, and BH-LYP functionals. The time-dependent Hartree-Fock (TDHF) method was included as an "upper limit" for the HF-exchange part in the functional. In general, it is found that the accuracy of most of the simulated spectra (except those from TDHF) is good enough to assign absolute configurations of chiral molecules with very high certainty. However, the description of weakly disturbed, inherently achiral chromophores and systems with Rydberg-valence mixing turned out to be rather difficult. Furthermore, none of the methods perform reliably for all of the molecules in the test suite, and in particular, the TDDFT results are very sensitive to the functional used. The best overall performance is achieved with the DFT/MRCI and CC2 methods. The TDDFT method should be used carefully, especially for systems with important diffuse or charge-transfer states. Out of the three functionals tested, B3-LYP seems to perform best. In practice, we highly recommend the simultaneous application of different complementary single and multireference methods, which significantly increases the reliability of theoretical predictions.