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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Interaction Energies of Hydrogen-Bonded Formamide Dimer, Formamidine Dimer, and Selected DNA Base Pairs Obtained with Large Basis Sets of Atomic Orbitals
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Interaction Energies of Hydrogen-Bonded Formamide Dimer, Formamidine Dimer, and Selected DNA Base Pairs Obtained with Large Basis Sets of Atomic Orbitals

机译：氢键结合的甲酰胺二聚体，甲am二聚体和选定的DNA碱基对的相互作用能，这些碱基对是通过大的原子轨道集获得的

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Interaction energies of selected H-bonded nucleic acids base pairs, formamide dimer, and formamidine dimer have been evaluated using the second-order Moller-Plesset method (MP2) with extended basis sets of atomic orbitals. Basis sets with two sets of d-polarization functions on each non-hydrogen atom give the same interaction energies as medium-sized 6-31G~(**) and 6-31G~*(0.25) basis sets. This is due to a compensation of errors in the evaluation of the Hartree-Fock and correlation interaction energies. With a further increase of the size of the basis set, a steep improvement (increase in absolute value) of the interaction energy appears. It amounts to 0.6-1.1 kcal/mol with the cc-pVTZ basis set. The aug-cc-pVQZ and cc-pV5Z basis sets improve the interaction energy of model complexes by additional ca. 1.3 kcal/mol while these data appear to be very close to the basis set limit. In contrast to the MP2 method, Becke3LYP density functional theory method does not show any systematic improvement of the interaction energies with the increase of the basis set size. The previously published reference values for interaction energies of H-bonded base pairs obtained with medium-sized basis sets of atomic orbitals are likely to be underestimated (in absolute value) by 2.0-2.5 kcal/mol while relative stabilities of base pairs are correctly reproduced. Nevertheless, with the present computer facilities we cannot yet investigate in detail the influence of the quality of the optimized geometries of the dimers on their stabilization energies. It is expected, however, that this contribution is considerably smaller compared to the primary basis set effects evaluated in this study.
机译：所选的H键合核酸碱基对，甲酰胺二聚体和甲am二聚体的相互作用能已使用二阶Moller-Plesset方法（MP2）与扩展的原子轨道基础集进行了评估。在每个非氢原子上具有两组d极化函数的基组提供与中型6-31G〜（**）和6-31G〜*（0.25）基组相同的相互作用能。这是由于补偿了Hartree-Fock和相关相互作用能的评估中的误差。随着基础集合的大小的进一步增加，相互作用能出现了急剧的改善（绝对值的增加）。以cc-pVTZ为基准，其值为0.6-1.1 kcal / mol。 aug-cc-pVQZ和cc-pV5Z基集通过额外的ca来提高模型复合体的相互作用能。 1.3 kcal / mol，而这些数据似乎非常接近基准设定极限。与MP2方法相反，Becke3LYP密度泛函理论方法并未显示出随着基数集大小的增加，相互作用能的任何系统性改进。使用中等大小的原子轨道基本集获得的H键合碱基对的相互作用能的先前发布的参考值可能被低估了2.0-2.5 kcal / mol（绝对值），同时正确再现了碱基对的相对稳定性。然而，利用目前的计算机设备，我们还不能详细研究二聚体的最佳几何形状的质量对其稳定能量的影响。但是，与本研究中评估的主要基础设置效果相比，预计该贡献要小得多。

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