Rigid Body Approximation for the Anharmonic Description of Molecule-Surface Vibrations.
Rigid Body Approximation for the Anharmonic Description of Molecule-Surface Vibrations.
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分子表面振动非简谐描述的刚体近似
DOI：
10.1021/acs.jctc.2c00597
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发表时间：
--
影响因子：
5.5
通讯作者：
J. Sauer
中科院分区：
文献类型：
--
作者：
M. Rybicki;J. Sauer
我们提出了一种基于Rodrigues旋转公式的分子表面振动的非调和方法，该方法采用刚体坐标来描述分子沿正常模式的曲线位移（旋转和平移）。这些位移用于计算能量数据点，其中一维多项式势用三次样条拟合。在这些势中，分别对六种刚体模态中的每一种，用谐振子或傅立叶函数（纯旋转）作为基集求解一维Schrödinger方程。所得的非调和振动能用于计算配分函数，并由此计算吸附的焓、熵和吉布斯自由能。我们的数值实现已经成功地测试了莫尔斯和余弦电位与已知的解析解。该方法已应用于ch4在chabazite分子筛（H-CHA）质子形态的羟基上的吸附，以及ch4和CO在金属有机骨架（MOF） Mg2（dobdc）的Mg2+离子上的吸附。为了获得热力学函数的最佳估计，我们考虑了分子表面振动和系统内部振动在谐波水平上的耦合。计算的吉布斯自由能表明CH4/H-CHA与CO/MOF的耦合较小（在−0.7 ~ +0.1 kJ/mol之间），而CH4/MOF的耦合较大（−3.4 kJ/mol）。CH4/H-CHA、CH4/MOF和CO/MOF的非调和效应分别为- 4.7、0.3±0.7和- 2.4±0.6 kJ/mol，与实验值的偏差分别为+4.2、+0.9±0.7和- 0.4±0.6 kJ/mol。这完全符合MOF中ch4和CO吸附的化学精度限制（±4.2 kJ/mol）。CH4/H-CHA的较大偏差，在化学精度范围的边缘，很可能是由于软沸石模式的贡献，在我们的方法中被忽略了。
We present an anharmonic approach for molecule–surface vibrations that employs rigid body coordinates, based on the Rodrigues rotation formula, to describe curvilinear displacements (rotations and translations) of the molecule along normal modes. These displacements are used to calculate energy data points from which one-dimensional polynomial potentials are fitted using cubic splines. In these potentials, for each of the six rigid body modes separately, one-dimensional Schrödinger equations are solved with harmonic oscillator or Fourier functions (for pure rotations) as basis sets. The anharmonic vibrational energies obtained are used to calculate partition functions and from them enthalpies, entropies, and Gibbs free energies of adsorption. Our numerical implementation has been successfully tested for Morse and cosine potentials with known analytical solutions. The methods have been applied to adsorption of CH4on the hydroxyl group of the proton form of the chabazite zeolite (H-CHA), as well as to adsorption of CH4and CO on the Mg2+ions of the metal–organic framework (MOF) Mg2(dobdc). To obtain the best estimates for thermodynamic functions, we include the coupling between molecule–surface vibrations and intrasystem vibrations at the harmonic level. The calculated Gibbs free energies show that the coupling is small for CH4/H-CHA and CO/MOF (between −0.7 and +0.1 kJ/mol) but substantial for CH4/MOF (−3.4 kJ/mol). The predicted anharmonic effect on the Gibbs free energy of adsorption for CH4/H-CHA, CH4/MOF, and CO/MOF is −4.7, 0.3 ± 0.7, and −2.4 ± 0.6 kJ/mol, respectively, which results in +4.2, +0.9 ± 0.7, and −0.4 ± 0.6 kJ/mol, respectively, for the deviation from experiment. This is well within chemical accuracy limits (±4.2 kJ/mol) for the adsorption of CH4and CO in the MOF. The larger deviation for CH4/H-CHA, at the edge of the chemical accuracy range, is most likely due to contributions from soft zeolite modes which are neglected in our approach.
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DOI：
10.1002/anie.202013671
发表时间：
2021-02-15
期刊：
Angewandte Chemie (International ed. in English)
影响因子：
--
作者：
Berger F;Sauer J
通讯作者：
Sauer J
影响因子：
5.5
作者：
Amsler, Jonas;Plessow, Philipp N.;Bucko, Tomas
通讯作者：
Bucko, Tomas
影响因子：
5.5
作者：
Galimberti DR;Sauer J
通讯作者：
Sauer J
影响因子：
--
作者：
HOBZA, P;SAUER, J;ZAHRADNIK, R
通讯作者：
ZAHRADNIK, R
影响因子：
3.7
作者：
G. Piccini;Maristella Alessio;J. Sauer;Yuchun Zhi;Yuanshuai Liu;R. Kolvenbach;A. Jentys;J. Lercher
通讯作者：
G. Piccini;Maristella Alessio;J. Sauer;Yuchun Zhi;Yuanshuai Liu;R. Kolvenbach;A. Jentys;J. Lercher