Rybkin Vladimir V, VandeVondele Joost
Nanoscale Simulations, Department of Materials, ETH Zürich , Wolfgang-Pauli-Str. 27, CH-8093 Zürich, Switzerland.
J Phys Chem Lett. 2017 Apr 6;8(7):1424-1428. doi: 10.1021/acs.jpclett.7b00386. Epub 2017 Mar 17.
Nuclear quantum effects (NQEs) on the reduction and oxidation properties of small aqueous species (CO, HO, and O) are quantified and rationalized by first-principles molecular dynamics and thermodynamic integration. Vertical electron attachment, or electron affinity, and detachment energies (VEA and VDE) are strongly affected by NQEs, decreasing in absolute value by 0.3 eV going from a classical to a quantum description of the nuclei. The effect is attributed to NQEs that lessen the solvent response upon oxidation/reduction. The reduction of solvent reorganization energy is expected to be general for small solutes in water. In the thermodynamic integral that yields the free energy of oxidation/reduction, these large changes enter with opposite sign, and only a small net effect (0.1 eV) remains. This is not obvious for CO, where the integrand is strongly influenced by NQEs due to the onset of interaction of the reduced orbital with the conduction band of the liquid during thermodynamic integration. We conclude that NQEs might not have to be included in the computation of redox potentials, unless high accuracy is needed, but are important for VEA and VDE calculations.
通过第一性原理分子动力学和热力学积分，对核量子效应（NQEs）对小水性物种（CO、HO和O）的还原和氧化性质的影响进行了量化和合理化分析。垂直电子附着（即电子亲和能）和脱离能（VEA和VDE）受到NQEs的强烈影响，从原子核的经典描述转变为量子描述时，其绝对值降低了0.3 eV。这种效应归因于NQEs减少了氧化/还原时的溶剂响应。溶剂重组能的降低对于水中的小溶质来说预计是普遍现象。在产生氧化/还原自由能的热力学积分中，这些大的变化以相反的符号进入，仅留下小的净效应（0.1 eV）。对于CO来说这并不明显，在热力学积分过程中，由于还原轨道与液体导带的相互作用开始，被积函数受到NQEs的强烈影响。我们得出结论，除非需要高精度，否则在氧化还原电位的计算中可能不必考虑NQEs，但它们对于VEA和VDE的计算很重要。
