表面吸附与解吸的从头计算统计力学：I. 低覆盖度下MgO(001)上的H$_2$O

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摘要翻译：
提出了一种基于分子动力学的通用计算方案计算材料表面热平衡吸附分子化学势的模拟。该方案基于M.D.中平均力的计算。在模拟中，选择的分子在表面上的高度受到限制，然后对平均力进行积分，得到平均力的势，从而得到化学势。该方案在任何覆盖范围和温度下都是有效的，因此原则上它允许计算化学势作为覆盖范围和温度的函数。除了对原子核使用经典统计力学外，它避免了所有统计力学近似，并且对吸附位点没有预先假定。从化学势可以计算出分子的绝对解吸速率，前提是表面的平衡速率快于解吸速率。我们用{em从头算}M.D.方法应用该理论。用交换相关的Perdew-Burke-Ernzerhof(PBE)形式模拟了MgO(001)上低覆盖极限下的H$_2$O情况。计算得到了一个Polanyi-Wigner频率前因数的{\em从头算}值，该值比过去通常假定的$10^{13}$s$^{-1}$高出两个数量级以上。与实验的初步比较表明，PBE的吸附能可能太低，但需要将计算扩展到更高的复盖层才能得出确切的结论。指出了利用路径积分模拟包括量子核效应的可能性。
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英文标题：
《Ab initio statistical mechanics of surface adsorption and desorption: I.
  H$_2$O on MgO (001) at low coverage》
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作者：
D. Alfe` and M. J. Gillan (University College London)
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最新提交年份：
2007
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分类信息：

一级分类：Physics        物理学
二级分类：Statistical Mechanics        统计力学
分类描述：Phase transitions, thermodynamics, field theory, non-equilibrium phenomena, renormalization group and scaling, integrable models, turbulence
相变，热力学，场论，非平衡现象，重整化群和标度，可积模型，湍流
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一级分类：Physics        物理学
二级分类：Materials Science        材料科学
分类描述：Techniques, synthesis, characterization, structure.  Structural phase transitions, mechanical properties, phonons. Defects, adsorbates, interfaces
技术，合成，表征，结构。结构相变，力学性质，声子。缺陷，吸附质，界面
--

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英文摘要：
  We present a general computational scheme based on molecular dynamics (m.d.) simulation for calculating the chemical potential of adsorbed molecules in thermal equilibrium on the surface of a material. The scheme is based on the calculation of the mean force in m.d. simulations in which the height of a chosen molecule above the surface is constrained, and subsequent integration of the mean force to obtain the potential of mean force and hence the chemical potential. The scheme is valid at any coverage and temperature, so that in principle it allows the calculation of the chemical potential as a function of coverage and temperature. It avoids all statistical mechanical approximations, except for the use of classical statistical mechanics for the nuclei, and assumes nothing in advance about the adsorption sites. From the chemical potential, the absolute desorption rate of the molecules can be computed, provided the equilibration rate on the surface is faster than the desorption rate. We apply the theory by {\em ab initio} m.d. simulation to the case of H$_2$O on MgO (001) in the low-coverage limit, using the Perdew-Burke-Ernzerhof (PBE) form of exchange-correlation. The calculations yield an {\em ab initio} value of the Polanyi-Wigner frequency prefactor, which is more than two orders of magnitude greater than the value of $10^{13}$ s$^{-1}$ often assumed in the past. Provisional comparison with experiment suggests that the PBE adsorption energy may be too low, but the extension of the calculations to higher coverages is needed before firm conclusions can be drawn. The possibility of including quantum nuclear effects by using path-integral simulations is noted.
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PDF链接：
https://arxiv.org/pdf/706.1

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关键词：统计力学 Calculations Calculation Statistical equilibrium 方案 PBE 理论 解吸 计算