The ClH⋯FH and FH⋯ClH configurations of the mixed HF/HCl dimer (where the donor⋯acceptor notation indicates the directionality of the hydrogen bond) as well as the transition state connecting the two configurations have been optimized using MP2 and CCSD(T) with correlation consistent basis sets as large as aug‐cc‐pV(5 + d)Z. Harmonic vibrational frequencies confirmed that both configurations correspond to minima and that the transition state has exactly one imaginary frequency. In addition, anharmonic vibrational frequencies computed with second‐order vibrational perturbation theory (VPT2) are within 6 cm−1 of the available experimental values and deviate by no more than 4 cm−1 for the complexation induced HF frequency shifts. The CCSD(T) electronic energies obtained with the largest basis set indicate that the barrier height is 0.40 kcal mol−1 and the FH⋯ClH configuration lies 0.19 kcal mol−1 below the ClH⋯FH configuration. While only modestly attenuating the barrier height, the inclusion of either the harmonic or anharmonic zero‐point vibrational energy effectively makes both minima isoenergetic, with the ClH⋯FH configuration being lower by only 0.03 kcal mol−1. © 2018 Wiley Periodicals, Inc.

中文翻译：

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混合 HF/HCl 二聚体中的氢键：给予或接受更好？

混合 HF/HCl 二聚体的 ClH⋯FH 和 FH⋯ClH 构型（其中供体⋯受体符号表示氢键的方向性）以及连接这两种构型的过渡态已使用 MP2 和 CCSD(T ) 具有与 aug-cc-pV(5 + d)Z 一样大的相关一致基组。谐波振动频率证实，两种配置都对应于最小值，并且过渡态恰好具有一个虚频率。此外，使用二阶振动微扰理论 (VPT2) 计算的非谐振动频率在可用实验值的 6 cm-1 范围内，并且对于络合引起的 HF 频移偏差不超过 4 cm-1。用最大基组获得的 CCSD(T) 电子能量表明势垒高度为 0。40 kcal mol−1 和 FH⋯ClH 构型比 ClH⋯FH 构型低 0.19 kcal mol−1。虽然仅适度衰减势垒高度，但包含谐波或非谐波零点振动能有效地使两者的最小值等能，ClH⋯FH 构型仅低 0.03 kcal mol-1。© 2018 Wiley Periodicals, Inc.