Computational Studies of Collision-Induced Polymerization and Thin-Film Growth

理论和计算化学项目正在支持肯塔基大学的辛诺特教授。这项工作也由材料研究部的资金共同资助。这项研究将研究有机分子团簇在超热(约5-80 eV/分子)和keV入射能量下撞击表面时发生的力学和化学过程。这种方法将是分子动力学模拟，其中作用在团簇和表面上的单个原子的力是从多体经验势获得的。这些结果将通过使用紧束缚近似方法重复较小的模拟并与实验进行比较来检验。这项研究将提供在团簇-固体-表面碰撞的高压条件下发生的化学反应类型的信息，详细说明这些反应的机理，揭示化学产品的类型和产量，并记录表面的任何结构变化。他们还将揭示化学反应如何依赖于一系列因素，包括表面反应性和团簇分子物种、大小和入射动能。团簇-固体-表面碰撞是粒子-表面相互作用领域中最有趣的话题之一。一些可能的结果包括团簇内的化学反应产生新的化学产品，以及团簇材料在表面生长出薄薄的涂层。然而，尽管碳氢化合物材料(如石油产品和钻石)在科学和技术上具有重要意义，但关于这种碰撞过程中发生的化学物质，特别是涉及碳簇和氢簇的化学物质，有许多未知之处。这项研究将使用计算机模拟来研究当这些分子团簇以与爆炸和星际空间中发生的速度相当的速度撞击表面时发生的机械和化学过程。研究结果将提供在团簇-固体-表面碰撞的高压条件下发生的化学反应类型的信息，并揭示化学产品的种类和产量。它们还将显示发生的化学反应如何随着反应条件的变化而变化。

The Theoretical and computational Chemistry Program is supporting Professor Sinnott at the University of Kentucky. This work is also cofunded by funds from the Division of Materials Research. This research will investigate the mechanical and chemical processes which occur when organic molecular clusters impact surfaces at hyperthermal (about 5-80 eV/molecule) and keV incident energies. The approach will be molecular dynamics simulations where the forces on the individual atoms in the clusters and surfaces are obtained from many-body empirical potentials. These results will be checked by repeating the smaller simulations using tight-binding approximation methods and comparing to experiment. This study will provide information about the types of chemical reactions that occur under the high pressure conditions of cluster-solid- surface impacts, detail the mechanisms of these reactions, reveal the types and yields of chemical products, and document any structural changes to the surface. They will also reveal how the chemical reactions depend on a number of factors including surface reactivity and cluster molecular species, size and incident kinetic energy. Cluster-solid-surface collisions are one of the most interesting topics in the area of particle-surface interactions. Some of the possible outcomes include chemical reactions within the cluster to make new chemical products and the growth of thin coatings of the cluster material on the surface. However, there is much that is not known about the chemistry that occurs during such collisions, especially those that involve clusters of carbon and hydrogen, despite the scientific and technological importance of hydrocarbon materials (such as petroleum products and diamond). This research will use computational simulations to investigate the mechanical and chemical processes which occur when these molecular clusters impact surfaces at speeds comparable to those that occur during explosions and in interstellar space. The results will provide information about the types of chemical reactions that occur under the high pressure conditions of cluster-solid-surface impacts and reveal the variety and yields of chemical products. They will also show how the chemical reactions that take place vary with changes in the reaction conditions.