We determine the ionization potential (IP) and the electron affinity (EA) of liquid water together with the absolute redox level of the standard hydrogen electrode (SHE) by combining advanced electronic-structure calculations, ab initio molecular dynamics simulations, thermodynamic integration, and potential alignment at the water–vacuum interface. The calculated SHE level lies at 4.56 eV below the vacuum level, close to the experimental reference of 4.44 eV inferred by Trasatti. The band edges are determined through a hybrid functional designed to reproduce the band gap achieved with highly accurate GW calculations. Our analysis yields IP = 9.7 eV and EA = 0.8 eV, consistent with both photoemission spectra of liquid water and thermodynamical data for the hydrated electron.

中文翻译：

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液态水的绝对能级

我们通过结合先进的电子结构计算，从头算分子动力学模拟，热力学积分和定量分析，确定液态水的电离电势（IP）和电子亲和力（EA）以及标准氢电极（SHE）的绝对氧化还原水平。水-真空界面处的电位对准。计算得出的SHE水平在真空水平以下4.56 eV，接近于Trasatti推断的4.44 eV的实验参考值。通过混合功能确定带边缘，该混合功能旨在复制通过高精度GW计算获得的带隙。我们的分析得出IP = 9.7 eV和EA = 0.8 eV，与液态水的光发射光谱和水合电子的热力学数据一致。