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首页> 外文期刊>The journal of physical chemistry, A. Molecules, spectroscopy, kinetics, environment, & general theory >Ab Initio Benchmark Study of (2-Pyridone)_2, a Strongly Bound Doubly Hydrogen-Bounded Dimer
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Ab Initio Benchmark Study of (2-Pyridone)_2, a Strongly Bound Doubly Hydrogen-Bounded Dimer

机译：（2-吡啶酮）_2，一种强双氢键二聚体的从头算基准研究

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摘要

The 2-pyridone dimer, (2PY)_2, has two antiparallel N-H…O H-bonds analogous to nucleobase dimers. The gas-phase rotational constants and all six intermolecular vibrational frequencies of (2PY)_2 have been previously measured, providing benchmarks for theory. The structure, rotational constants, vibrational frequencies, and binding and dissociation energies of (2PY)_2 were calculated at the correlated level using second-order Moller-Plesset perturbation theory (MP2) with medium to very large basis sets. The MP2 binding energy limit was extrapolated to the complete basis set (CBS) as D_(e,CBS) = -22.62 ± 0.07 kcal/mol. Higher order correlation energy contributions to De at the CCSD(T) level are destabilizing (+0.77 kcal/mol). This implies that (2PY)_2 is the most strongly bound doubly hydrogen-bonded dimer known so far. The Hartree-Fock contribution to D_(e,CBS) is only ≈65%. Several medium-size basis sets yield MP2 D_e's within ±5% of the CBS value, as well as structure, rotational constants, and intermolecular vibrations in good agreement with experiment. The PW91 density functional method also shows very good performance with regard to all properties calculated, comparable to MP2. The results imply that correlated methods combined with carefully chosen medium-size basis sets may give near-quantitative results for the structures, binding energies, and intermolecular vibrational frequencies of nucleic acid base dimers.
机译：2-吡啶酮二聚体（2PY）_2具有两个与核碱基二聚体相似的反平行N-H…O H键。先前已测量了气相旋转常数和（2PY）_2的所有六个分子间振动频率，为理论提供了基准。使用二阶Moller-Plesset微扰理论（MP2），以中等到非常大的基础集，在相关水平上计算（2PY）_2的结构，旋转常数，振动频率以及键合和离解能。 MP2的结合能极限被外推到完全基集（CBS），即D_（e，CBS）= -22.62±0.07 kcal / mol。在CCSD（T）水平上对De的高阶相关能量贡献正在不稳定（+0.77 kcal / mol）。这意味着（2PY）_2是迄今为止已知的最牢固结合的氢键结合的二聚体。 Hartree-Fock对D_（e，CBS）的贡献仅为≈65％。几个中等大小的基集所产生的MP2 D_e值在CBS值的±5％之内，并且在结构，旋转常数和分子间振动方面均与实验相吻合。在计算的所有特性方面，PW91密度泛函方法也显示出非常好的性能，可与MP2媲美。结果表明，相关方法与精心选择的中等大小基础集相结合，可以为核酸碱基二聚体的结构，结合能和分子间振动频率提供接近定量的结果。

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