Assessment of the CCSD and CCSD(T) coupled-cluster methods in calculating heats of formation for Zn complexes.
Assessment of the CCSD and CCSD(T) coupled-cluster methods in calculating heats of formation for Zn complexes.
复制标题
评估 CCSD 和 CCSD(T) 耦合簇方法在计算 Zn 配合物的生成热时的效果。
DOI：
10.1021/jp904241v
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发表时间：
2009
期刊：
影响因子：
--
通讯作者：
MerzJr,KennethM
中科院分区：
文献类型：
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作者：
Weaver,MichaelN;Yang,Yue;MerzJr,KennethM
用耦合团簇方法计算了一系列锌配合物的生成热。根据以前使用密度泛函方法进行的计算研究以及实验值对计算值进行了评估。用6-31G**和TZVP基组以及LANL2DZ-6-31G**(−-2DZ**)和LANL2DZ-−-TZVP杂化基组，在CCSD和CCSD(T)水平上测定了9个中性锌Xn络合物[X=−Zn，−H，−O，−F2，−S，−Cl2，−CH3，(−CH3)2]的生成热.CCSD(T)/6-31G**理论水平预测非烷基锌络合物的生成热最为准确。烷基锌物种是有问题的，因为没有一个被测试的方法准确地预测了这些络合物的生成热。在有实验几何参数的情况下，通过CCSD/6-31G**理论水平预测这些参数是最准确的；使用CCSD(T)并不能提高与实验值的一致性。对于给定的泛函/基组组合，耦合簇法没有提供比密度泛函理论计算更系统的改进。在6-31G**基组中，除ZnH和ZnF2外，其余多个密度泛函的计算结果均优于耦合团簇计算。
Heats of formation were calculated using coupled-cluster methods for a series of zinc complexes. The calculated values were evaluated against previously conducted computational studies using density functional methods as well as experimental values. Heats of formation for nine neutral ZnXncomplexes [X = −Zn, −H, −O, −F2, −S, −Cl, −Cl2, −CH3, (−CH3)2] were determined at the CCSD and CCSD(T) levels using the 6-31G** and TZVP basis sets as well as the LANL2DZ-6-31G** (LACVP**) and LANL2DZ-TZVP hybrid basis sets. The CCSD(T)/6-31G** level of theory was found to predict the heat of formation for the nonalkyl Zn complexes most accurately. The alkyl Zn species were problematic in that none of the methods that were tested accurately predicted the heat of formation for these complexes. In instances where experimental geometric parameters were available, these were most accurately predicted by the CCSD/6-31G** level of theory; going to CCSD(T) did not improve agreement with the experimental values. Coupled-cluster methods did not offer a systemic improvement over DFT calculations for a given functional/basis set combination. With the exceptions of ZnH and ZnF2, there are multiple density functionals that outperform coupled-cluster calculations with the 6-31G** basis set.