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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Accurate Calculation of the Heats of Formation for Large Main Group Compounds with Spin-Component Scaled MP2 Methods
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Accurate Calculation of the Heats of Formation for Large Main Group Compounds with Spin-Component Scaled MP2 Methods

机译：用自旋组分标定MP2方法精确计算大型主族化合物的形成热

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Three MP2-type electron correlation treatments and standard density functional theory (DFT) approaches are used to predict the heats of formation for a wide variety of different molecules.The SCF and MP2 calculations are performed efficiently using the resolution-of-the-identity (RI) approximation such that large basis set (i.e.,polarized valence quadruple-delta quality) treatments become routinely possible for systems with 50-100 atoms.An atom equivalent scheme that corrects the calculated atomic energies is applied to extract the "real" accuracy of the methods for chemically relevant problems.It is found that the spin-component-scaled MP2 method (SCS-MP2,J.Chem.Phys,2003,118,9095) performs best and provides chemical accuracy (MAD of 1.18 kcal/mol) for a G2/97 test set of molecules.The computationally more economical SOS-MP2 variant,which retains only the opposite-spin part of the correlation energy,is slightly less accurate (MAD of 1.36 kcal/mol) than SCS-MP2.Both spin-component-scaled MP2 treatments perform significantly better than standard MP2 (MAD of 1.77 kcaymol) and DFT-B3LYP (MAD of 2.12 kcal/mol).These conclusions are supported by results obtained for a second test set of complex systems containing 70 molecules,including charged,strained,polyhalogenated,hypervalent,and large unsaturated species (e.g.C_(60)).For this set,DFT-B3LYP performs badly (MAD of 8.6 kcal/mol) with many errors > 10-20 kcal/mol while the spin-component-scaled MP2 methods are still very accurate (MAD of 2.8 and 3.7 kcal/mol,respectively).DFT-B3LYP shows an obvious tendency to underestimate molecular stability as the system size increases.Out of six density functionals tested,the hybrid functional PBEO performs best.All in all,the SCS-MP2 method,together with large AO basis sets,clearly outperforms current DFT approaches and seems to be the most accurate quantum chemical model that routinely can predict the thermodynamic properties of large main group compounds.
机译：三种MP2型电子相关处理和标准密度泛函理论（DFT）方法用于预测各种不同分子的形成热.SCF和MP2的计算使用相同的分辨度（ RI）近似，这样对于具有50-100个原子的系统，通常可以进行大的基集（即极化价四重原子-增量质量）处理。采用原子等价方案来校正计算的原子能，以提取原子的“真实”精度。发现自旋组分定标的MP2方法（SCS-MP2，J.Chem.Phys，2003,118,9095）表现最佳，并且提供了化学精度（MAD为1.18 kcal / mol）。对于G2 / 97分子测试集而言，在计算上更经济的SOS-MP2变体（仅保留相关能量的反旋部分），其准确度（MAD为1.36 kcal / mol）比SCS-MP2稍差。自旋分量尺度ed MP2处理的效果明显优于标准MP2（MAD为1.77 kcaymol）和DFT-B3LYP（MAD为2.12 kcal / mol）。第二个测试结果由包含70个分子的复杂系统（包括带电，应变，多卤代，高价和大不饱和物种（例如C_（60））。对于该组，DFT-B3LYP的性能较差（MAD为8.6 kcal / mol），并且许多误差大于10-20 kcal / mol，而自旋组分大规模的MP2方法仍然非常准确（MAD分别为2.8 kcal / mol和3.7 kcal / mol）。随着系统规模的增加，DFT-B3LYP表现出明显低估分子稳定性的趋势。在测试的六种密度官能团中，杂合官能团PBEO表现出色总而言之，SCS-MP2方法与大型AO基集一起明显胜过当前的DFT方法，并且似乎是常规上可以预测大型主族化合物热力学性质的最精确的量子化学模型。

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