Zeolite Adsorption Free Energies from ab Initio Potentials of Mean Force
Zeolite Adsorption Free Energies from ab Initio Potentials of Mean Force
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DOI：
10.1021/acs.jctc.7b00716
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发表时间：
2018-02-01
影响因子：
5.5
通讯作者：
Schneider, William F.
中科院分区：
文献类型：
--
作者：
Li, Hui;Paolucci, Christopher;Schneider, William F.
金属交换沸石化学吸附小气体分子的能力是其作为非均相催化剂和气体分离剂的性能的关键。在这里，我们提出并评估了一个从头算的平均力势（PMF）的方法计算有代表性的小分子的吸附自由能的铜交换网站在SSZ-13沸石。我们发现，铜离子被动员的吸附物，因此，计算的自由能是显着更负比从传统的谐振子模型。PMF衍生的自由能与现有的实验是一致的，在许多情况下，与基于动力学的准谐波分析（QHA）。PMF方法避免了QHA固有的自由度的人工划分。的PMF结果的基础上，我们提出了一个简单的相关性来估计从计算的吸附能和气相熵的自由能。
The ability of metal-exchanged zeolites to chemisorb small gas molecules is key to their performance as heterogeneous catalysts and gas-separating agents. Here, we propose and evaluate an ab initio potential of mean force (PMF) method for computing adsorption free energies of representative small molecules to Cu-exchanged sites in SSZ-13 zeolite. We show that Cu ions are mobilized by adsorbates and, as a result, computed free energies are significantly more negative than those obtained from a conventional harmonic oscillator model. PMF-derived free energies are consistent with available experiment and, in many cases, with a dynamics based quasi-harmonic analysis (QHA). The PMF approach avoids the artificial partitioning of degrees of freedom intrinsic to the QHA. On the basis of the PMF results, we propose a simple correlation to estimate free energies from computed adsorption energies and gas-phase entropies.