原子、分子与金属表面相互作用的动力学研究

【作者】 陈守刚；

【导师】 王泽新；

【作者基本信息】 山东师范大学 ， 物理化学， 2001， 硕士

【摘要】 原子、分子同金属表面的相互作用是多相催化，气体腐蚀以及晶体生长等领域研究中的一个重要课题。从分子水平上进行理论研究，不仅有助于认识吸附质和金属表面的相互作用机理，而且可以获得吸附、表面扩散等动力学信息。本论文选取了一些具有典型意义的原子和双原子分子通过5-参数Morse势和改进的推广的LEPS势方法研究了原子、分子在过渡金属平坦和缺陷表面的吸附解离的动力学行为。该方法的优点在于：（1）优选的5-参数是与表面结构无关的，不仅适合平坦的金属表面，也适合于台阶面；（2）在处理分子与表面相互作用体系时，把推广的LEPS势方法中的原子与表面相互作用势用5-参数Morse势代替，同时在三个低指数表面优选了一组与表面结构无关的sato参数，这样处理得到的推广的LEPS势也是表面结构无关的，并且可应用到台阶面的模拟；（3）可选用足够大的Cluster来模拟理想的平坦和缺陷表面。 同时，我们的工作还提出了一种构造三原子H₂O分子的相互作用势的方法-多体Morse势，并使用QCT方法在势能面上进行了动力学计算。 全文共分四部分： 第一章，前言，论述了研究意义、研究吸附的理论现状和实验方法以及本文方法的优点。详细的介绍了5-参数Morse势改进的推广的LEPS势方法。 第二章，应用5-参数Morse势详细研究了的O-Pd和N-Ni相互作用体系的吸附临界点特性和扩散势能面结构，并推广到O-Pd（115）和N-Ni（510）体系，研究了台阶对原子吸附和扩散的影响。对照实验结果表明，我们的方法是可信和可用的。 第三章，应用改进的推广的LEPS势方法详细的研究了的NO-Ni、 陈守刚：山东师范大学硕士学位论文OH－Ni和O。Fd相互作用体系的吸附临界点特性和解离扩散势能面结构，并考察了 Ni（510）台阶面对 NO分子解离吸附的影响。研究结果表明。 （l）在台阶下部，分子直接解离的最低能量反应途径密度增大，且平动活化垒降低．（2）在台阶上部及台阶边棱处，前驱态的吸附能减小，分子复合脱附几率增加．因而，台阶处成为分子解离和复合的活性部位．上述结果同时表明，分子解离至少需要两个最近邻活性空位，这也正是表面高覆盖度下解离被阻止的原因．我们的计算结果较好的描述了实验探测的结果，这表明我们的理论计算模型是可行的。 第四章，详细探讨了多体Morse势方法模拟Hp分子的解析势能面，该方法支持了O／D)＋H。反应以垂直插入为主，共线抽提反应需越过能垒。该方法较好的符合了实验结果。动力学计算表明：初始转动量子数对反应截面影响很小，某一平动能下，产物的振转分布态随振动态的增加而逐渐减少。更多还原

【Abstract】 The interaction between atoms, molecules and metallic surfaces is an important research topic in the field of heterogeneous catalysis, gas erosion and crystal growth. Theoretical study on a molecular level can not only help understand the interaction mechanism between the absorbent and metallic surfaces, but also acquire the kinetic information of adsorption and surface diffusion. Some representative atoms and molecules are selected to study the kinetic behavior of adsorption and dissociation on the flat and defective surfaces by employing five-parameter Morse potential and improved extended LEPS potential in this dissertation. This method has three merits: (1) The five parameters are irrespective of surface structure. They can be employed in the flat and defective surfaces at the same time. (2) When dispose the interaction between molecule and surface, we replace the atom-surface potential of extended LEPS potential with five-parameter Morse potential. When we synchronously adjust three Sato parameters on three low index surfaces, the interaction potential between molecular and surface is surely independent of the metallic surface structure. It can also be employed to the defective surfaces. (3) This method employs sufficiently large Cluster to simulate ideal flat plane and defective terrace. Simultaneity, we put forward a method---multi-body Morse potential梩o construct the interaction potential of H20. Kinetic calculation was simulated on the potential energy surface by QCT method. The whole paper is divided into four chapters. 73 Chapter 1, Preface, it describes the meaning of study, the experimental and theoretical methods in studying the adsorption. Morse potential method and improved extended LEPS potential method were introduced in detail. Chapter 2, 5-parameter Morse potential method is employed to study the interactional systems of 0-Pd and N-Ni about the characteristic of adsorptive critical point and the structure of diffused potential energy surface. Moreover, this method was also employed to study the interactional systems of 0-Pd (115) and N-Ni (510) ,to discussed the effect of step about the adsorptive diffusion of atom. Our theoretical results are in agreement with experimental results. This indicates that our method is credible and usable. Chapter 3, Improved extended LEPS potential method is employed to study the interactional systems of NO-Ni, OH-Ni and 02-Pd about the characteristic of adsorptive critical point and dissociative diffusion potential energy surface. Moreover, this method was also employed to study the effect of Ni (510) step terrace about the dissociative adsorption of NO. The role of the step is that (1) at the terraces under the step, the direct dissociative paths are increased and the translational activation potential barriers are decreased obviously. (2) at the terraces above the step and near step edge, the precursor adsorptive energies are decreased, the desorption paths are increased. Thus the step are the active regions for the dissociation and association of molecule. These results simultaneous indicate that the dissociation of molecular requires at least two adjacent empty sites, which show why dissociation is inhibited at high coverage. Our theoretical results are in agreement with experimental更多还原