Theoretical Study of Photodissociation Dynamics in the Gaseous and Condensed Phases

Hua Guo在托莱多大学得到了NSF理论和计算化学计划的支持，用于化学反应动力学的理论研究。这项工作的关注点是光解离的研究，特别是，时间相关的量子力学将用于研究小分子的光解离动力学。这些过程将在气相、表面和溶液中进行研究。 为了处理后两种情况下的问题，将开发一种新的理论程序，这是一种结合量子和经典方法的混合方法。通过这种混合方法，分子反应的量子特征得到了适当的处理，但介质、底物或溶剂的影响也被包括在内。对于气相的研究，一些中等大小的多原子分子将被处理，这些包括稀有气体配合物和甲基配合物的莱德格激发态。 一般而言，光诱导化学的动力学，特别是光解离的动力学，取决于系统中原子之间的相互作用能的细节;即，势能面的细节。然而，将该表面的特征与反应产物的特性和这些产物上的能量分布联系起来并不简单。本计画所进行的光解离研究将增进对相关关系的了解。特别是，工作的两个方面有助于确保它将对这一重要的科学目标产生相当大的影响。首先，正在进行的工作是密切接触，并经常与实验人员合作。正因为如此，用于获得潜在的势能面以及用于研究的反应的时间依赖的量子特征的近似可以被验证。其次，被研究的系统是经过精心挑选的，以产生重要和有用的信息。 它们足够小，可以进行高精度的量子力学处理，但又足够大，可以包含化学键和其他与光化学中更一般问题相关的特征。

Hua Guo at the University of Toledo is supported by the NSF Theoretical and Computational Chemistry Program for theoretical investigations of chemical reaction dynamics. The concern of this work is the study of photodissociation; in particular, time dependent quantum mechanics will be used to study the photodissociation dynamics of small molecules. These processes will be studied in the gas phase, on surfaces, and in solution. In order to treat problems in the later two cases, a new theoretical procedure will be developed which is a hybrid approach combining quantum and classical methods. With this hybrid approach, the quantum features of the molecular reaction are properly addressed but the effects of the medium, substrate or solvent, are included. For the gas phase studies, a few modest size polyatomic molecules will be treated; these include rare gas complexes and Ryderg excited states of methyl complexes. The dynamics of photo-induced chemistry, in general, and of photodissociation, in particular, depend on the details of the interaction energies among the atoms in the system; i.e., on the details of the potential energy surfaces. However, it is not simple to relate the features of this surface to the identity of the reaction products and to the energy distribution over these products. The studies of photodissociation being carried out in this project will enhance the understanding of the relevant relationships. In particular, two aspects of the work help to insure that it will have considerable impact on this important scientific goal. First, the work is being carried out is close contact and, often, in collaboration with experimentalists. Because of this, the approximations used to obtain the underlying potential energy sufaces as well as those used to study the time dependent quantum features of the reaction can be validated. Second, the systems being studied are carefully chosen to yield important and useful information. They are sufficiently small to be tractable for high accuracy quantum mechanical treatments yet sufficiently large to contain chemical bonds and other features relevant to more general problems in photochemistry.