A Theoretical Investigation of Molecular Ground and Excited States

在这项研究中，在化学系的理论和计算化学计划中，从头算电子结构方法被用来研究分子体系的基态和激发态。重点是各种多参考相关方法的比较和组合摄动-变分方法的检验。应用包括研究避开交叉附近的双原子分子的激发态，多烯和其他共轭物种的低激发态，以及对称和不对称的碱卤化物二聚体的基态性质。这项研究使用基于计算机的现代计算方法来表征一些不同类型的分子在它们的基态和激发态中的能量和形状。这些分子类型包括氧、一氧化碳和氢化铝等硅藻类，各种碳氢化合物，以及由两个氯化钠分子结合在一起形成的高温物种。

In this study in the Theoretical and Computational Chemistry Program in the Division of Chemistry ab initio electronic structure methods are being used to study the ground and excited states of molecular systems. The focus is on the comparison of various multi-reference correlation methods and on the testing of combined perturbative-variational approaches. Applications include studies of excited states of diatomic molecules near avoided crossings, low-lying excited states of polyenes and other conjugated species, and the ground-state properties of both symmetrical and asymmetrical alkali halide dimers. %%% Modern computer-based computational methods are being used in this study to characterize the energies and shapes of a number of different types of molecules both in their ground and excited states. These molecular types include diatomics such as oxygen, carbon monoxide, and aluminum hydride, various hydrocarbons, and such high-temperature species as that formed by two sodium chloride molecules bound together.