Daub Christopher D, Patey G N, Jack D B, Sallabi A K
Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada.
J Chem Phys. 2006 Mar 21;124(11):114706. doi: 10.1063/1.2171277.
The adsorption of CO2 gas on the MgO (100) crystal surface is investigated using grand canonical Monte Carlo simulations. This allows us to obtain adsorption isotherms that can be compared with experiment, as well as to explore the possible formation of monolayers of different densities. Our model calculations agree reasonably well with the available experimental results. We find a "low-density" adsorbed monolayer where each CO2 molecule is bound to two Mg2+ ions on the MgO substrate. We also observe the formation of monolayers of higher density, where some of the CO2 molecules have rotated and tilted to expose additional binding sites. Low-temperature simulations of both the low- and high-density monolayers reveal that these states are very close in energy, with binding energies of approximately 7 kcal/mol at T=5 K. The high-density monolayer given by our model has a density that is significantly less than the reported experimental value. We discuss this discrepancy and offer suggestions for resolving it.
利用巨正则蒙特卡罗模拟研究了CO₂气体在MgO(100)晶体表面的吸附。这使我们能够获得可与实验进行比较的吸附等温线，并探索不同密度单分子层的可能形成情况。我们的模型计算与现有的实验结果相当吻合。我们发现了一个“低密度”吸附单分子层，其中每个CO₂分子与MgO基底上的两个Mg²⁺离子结合。我们还观察到了更高密度单分子层的形成，其中一些CO₂分子发生了旋转和倾斜，以暴露更多的结合位点。对低密度和高密度单分子层的低温模拟表明，这些状态在能量上非常接近，在T = 5 K时结合能约为7 kcal/mol。我们模型给出的高密度单分子层的密度明显小于报道的实验值。我们讨论了这种差异并提出了解决它的建议。
