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首页> 外文期刊>The Journal of Chemical Physics >Combining density-functional calculations with kinetic models: NO/Rh(111)
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Combining density-functional calculations with kinetic models: NO/Rh(111)

机译：将密度泛函计算与动力学模型结合：NO / Rh（111）

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We present a dynamic Monte-Carlo model involving lateral interactions and different adsorption sites (top, fcc and hcp). Using this model in combination with kinetic parameters from UHV experiments and lateral interactions derived from DFT calculations we have reproduced the ordering behavior of NO on Rh(111) during adsorption and the temperature programmed desorption (TPD) of NO from Rh(111) under UHV conditions. The formation of c(4x2)-2NO domains at 0.50 ML coverage is shown to depend strongly on the next-next-nearest-neighbor repulsion between the NO adsorbates in our model. The formation of the (2x2)-3NO structure at higher coverage follows from the avoidance of the strong next-nearest-neighbor repulsion in favor of the occupation of the top sites. A single-site model was able to reproduce the experimental TPD, but the lateral interactions were at odds with the values of the DFT calculations. A three-site model resolved this problem. It was found that all NO dissociates during TPD for initial coverages of NO below 0.20 ML. The nitrogen atoms recombine at higher temperatures. For NO coverages larger than 0.20 ML, 0.20 ML NO dissociates while the rest desorbs. This is due to a lack of accessible sites on the surface, i.e., sites where a molecule can bind without experiencing large repulsions with neighboring adsorbates. For NO coverages above 0.20 ML, the dissociation of NO causes a segregation into separate NO and N+O islands. The dissociation causes the surface to be filled with adsorbates, and the adsorbates are therefore pushed closer together. NO on one hand can easily be compressed into islands of 0.50 ML coverage, because there is no large next-next-nearest-neighbor repulsion. N+O on the other hand form islands with a lower coverage (0.30-0.35 ML) due to the considerable next-next-nearest-neighbor repulsion. Top bound NO (above 0.50 ML initial coverage) does not dissociate during TPD. It desorbs in a separate peak at 380 K. (C) 2003 American Institute of Physics. [References: 35]
机译：我们提出了一个动态的蒙特卡洛模型，其中涉及横向相互作用和不同的吸附位点（顶部，FCC和HCP）。使用此模型，结合超高压实验的动力学参数和DFT计算得出的横向相互作用，我们再现了吸附过程中NO在Rh（111）上的有序行为以及在超高压下Rh（111）上NO的程序升温脱附（TPD）。条件。在0.50 ML覆盖率下，c（4x2）-2NO域的形成在很大程度上取决于我们模型中NO吸附物之间的下一个下一个近邻排斥。 （2x2）-3NO结构在较高覆盖率下的形成是由于避免了强烈的下一个近邻排斥，从而有利于占据顶部站点。单点模型能够重现实验性TPD，但横向相互作用与DFT计算值不一致。三站点模型解决了这个问题。发现在TPD期间，对于初始覆盖量低于0.20 ML的NO，所有NO均发生解离。氮原子在较高温度下重组。对于大于0.20 ML的NO覆盖范围，0.20 ML NO会解离，而其余部分会解吸。这是由于表面上缺乏可及的位点，即分子可以结合而不会与相邻的吸附物发生大排斥的位置。对于高于0.20 ML的NO覆盖率，NO的解离会导致分离为单独的NO和N + O岛。解离使表面充满吸附物，因此将吸附物推近。一方面，NO不会轻易被压缩到0.50 ML覆盖的岛中，因为它没有较大的下一个最近邻居排斥。另一方面，由于相当多的下一个最近邻居排斥，N + O形成了具有较低覆盖率的岛（0.30-0.35 ML）。在TPD期间，上限NO（高于0.50 ML初始覆盖率）不会解离。在380 K处有一个单独的峰解吸。（C）2003美国物理研究所。 [参考：35]

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