Adsorbate Partition Functions via Phase Space Integration: Quantifying the Effect of Translational Anharmonicity on Thermodynamic Properties
Adsorbate Partition Functions via Phase Space Integration: Quantifying the Effect of Translational Anharmonicity on Thermodynamic Properties
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通过相空间积分的吸附配分函数：量化平移非谐性对热力学性质的影响
DOI：
10.1021/acs.jpcc.1c04009
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发表时间：
2021
期刊：
影响因子：
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通讯作者：
C. Goldsmith
中科院分区：
文献类型：
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作者：
Katrín Blöndal;K. Sargsyan;David H. Bross;B. Ruscic;C. Goldsmith
提出了一种计算金属表面吸附的非简谐热物性的新方法。用经典的蒙特卡罗相空间积分方法计算了氢原子在铜(111)面上运动的配分函数。在积分程序中使用了保极小的神经网络势能面。提出了两种不同的采样方案来生成训练数据，并使用了两种不同的密度泛函。通过使用离散变量表示，将结果与直接状态计数结果进行基准比较。相空间积分结果与基准结果具有很好的定量一致性。此外，离散变量表示和相空间积分结果都证实了H在Cu(111)面上的运动是高度非简谐的。在分压为0-1bar的范围内，计算了400、800和1200K下H_2解离吸附的自由能和相应的朗缪尔等温线。结果表明，非简谐效应导致氢的表面位分数显著高于预测值。
A new method for computing anharmonic thermophysical properties for adsorbates on metal surfaces is presented. Classical Monte Carlo phase space integration is performed to calculate the partition function for the motion of a hydrogen atom on Cu(111). A minima-preserving neural network potential energy surface is used within the integration routine. Two different sampling schema for generating the training data are presented, and two different density functionals are used. The results are benchmarked against direct state counting results by using discrete variable representation. The phase space integration results are in excellent quantitative agreement with the benchmark results. Additionally, both the discrete variable representation and the phase space integration results confirm that the motion of H on Cu(111) is highly anharmonic. The results were applied to calculate the free energy of dissociative adsorption of H2and the resulting Langmuir isotherms at 400, 800, and 1200 K in a partial pressure range of 0–1 bar. It shows that the anharmonic effects lead to significantly higher predicted surface site fractions of hydrogen.