Dynamics of Molecule-Surface Reaction and Unimolecular Dissociation

化学部的理论与计算化学项目支持张教授使用一种新颖的计算方法在化学动力学的一般领域进行了两项研究：(1)研究了氢在过渡金属上的解离吸附和缔合解吸；(2)研究了HF二聚体振动预解时的旋转态分布。这项工作涉及到大量的计算，这些计算是由计算机技术的最新进展和张教授开发的一种新的时变量子波包方法相结合而实现的。分子吸附在表面时的分裂和离开表面时的重组是催化过程中的两个基本步骤。在这项研究中，张教授应用了他开发的一项新技术，使对这些单个化学步骤的研究比以前更现实。目前的工作仅限于氢气作为吸附气体，但它将作为新的理论进展的测试，随着计算机技术的进步，这些理论进展可能会应用于更大的系统。同样的理论方法也被用于研究氢氟酸二聚体中氢键断裂时产物中的能量分布，并进行了进一步的测试。

The Theoretical and Computational Chemistry Program of the Chemistry Division has provided support to Professor Zhang to use a novel computational method to conduct two studies in the general area of chemical dynamics: (1) a study of dissociative adsorption and associative desorption of hydrogen on transition metals, and (2) an investigation of the rotational state distribution in the vibrational predissociation of the HF dimer. The work involves massive computations made possible by a combination of recent advances in computer technology and a new time-dependent quantum wave packet method that has been developed by Professor Zhang. %%% The breaking apart of molecules as they are adsorbed on a surface or their recombination as they leave the surface are two of the fundamental steps in catalytic processes. In this research, Professor Zhang applies a new technique he has developed to make possible a more realistic study of such individual chemical steps than has previously been possible. The present work is limited to hydrogen as the adsorbing gas, but it will serve as a test of the new theoretical advances which may be applied to larger systems later as computer technology advances. The same theoretical approach is also being used and further tested in a study of the energy distribution in the products when the hydrogen bond in the HF dimer is broken.