H₃O～+（T）的完整势能面计算及空穴-粒子对应在MRCISD中的应用

【作者】 翟高红；

【导师】 王育彬；

【作者基本信息】 西北大学 ， 理论物理， 2003， 博士

【摘要】 本文主要分为两个方面的工作：激发态H₃O⁺（T）全局势能面的构建和空穴-粒子对应算法在MRCISD程序中的应用。 在第一章，我们介绍了构造势能面的理论基础，包括数据点的计算、拟合，以及基于势能面的动力学计算。针对数据点的计算，我们主要介绍了目前较为流行的几种电子相关方法。鉴于多参考态方法在构建势能面时的重要性，文中重点讨论了MRCISD计算中的一些具体问题，如怎样选取参考态空间、对MRCISD的各种近似等，并对这些方法的优缺点作了简要评述。数据点的拟合是构建解析势能面的难点，我们介绍了几种常用的解析函数形式，以及拟合的一般思路和步骤，这一节是本论文的重点所在。对动力学计算的基础理论，文中也作了简单介绍。 H₃⁺离子与O原子的反应对星际云化学有着重要的意义，它为星际云中合成H₂O提供了可能的途径，为此，我们构造了激发态H₃O⁺（T）的全局势能面。第二章详细介绍了本文构建激发态H₃O⁺（T）全局势能面的方法和结果。我们用HONDO程序的CAS来选取参考态空间，采用多参考态的外收缩组态相互作用（MRECCISD）来计算数据点，最后用Aguado-Paniagua（AP）多体展开函数来拟合。通过本章的计算，我们对H₂O⁺（²B₁）和H₃O⁺（T）的全局势能面拓扑结构作了详细的研究，同时我们也建立了构筑三原子或四原子体系AP型多体展开势能面的一般方法和步骤。 第三章主要介绍空穴粒子对应在多参考态一级和二级组态相互作用（MRCISD）中的应用。我们采用不同于Paldus和Boyle的一种新的组态分类方法，定义了空穴LOOP形，根据从外空间LOOP形到空穴LOOP形的转化规则推导了总共244个空穴LOOP形的类型和数值，以此为基础提出了高效率的改进CI算法并将其程序化，给出了应用新算法程序的一些算例来说明新程序的功能和效率。算例结果表明，新程序有更高的效率，能大大节约存储所需的磁盘空间，可以容易地推广到更大规模的MRCISD计算。 在附录早，主要给出了四原子体系AP型势能面计算及拟合程序的源代码，这些拟合程序可以应用于任何四个或四个以下原子的体系。二原子势能曲线的拟合程序中还给出了常用光谱常数的计算。更多还原

【Abstract】 There are two main aspects in the doctoral dissertation, the construction of triplet H3O+ global potential energy surface (PES) and the applications of hole-particle correspondence in MRC1SD calculations.At Chapter 1. the theoretical basis of constructing the PES is presented, including the calculation, fitting and the dynamics study of the PES. On the calculation of data points, the most popular and well-developed post HF methods at present are discussed. Because it is most important to use the multi-reference methods when constructing the PES and investigating the chemical process, the realization and characteristics of MRCISD as well as its some approximations are discussed as the main subjects. Concise evaluation to these approximation methods and how to select the reference space are also discussed. Fitting the data points is the key process in the construction of the PES, and we have presented some basal analytic function form and the general process of fitting, too. At the end of this Chapter, some theories of dynamics calculation is introduced simply.The reaction of H3+ ion and 0 atom provides a pathway for synthesizing H2O in interstellar clouds, thus it has attracted a great deal of experimental and theoretical studies in the past few years. The aim of the Chapter 2 is to construct an accurate global PES of the triplet H3O+ based on the externally contracted multi-reference configuration interaction with single and doubly excitations (EC-MRCISD), which is developed by our research group. We use complete active space (CAS) of HONDO and MELD programs to select the reference space and the computed energies will be fitted as many-body expansion functions suggested by Aguado and Paniagua. By the way. the global PES of H2O+(2B1) is constructed. The results show that the fitted PESs are good. They will be helpful to study the reactions of H2O+(2B1) or triplet H3O+ in detail and accurately. At the same time, the general method of constructing three or four atomic system AP many-body expansion PES is developed.Chapter 3 introduces the applications of hole-particle correspondence in MRCISDcalculations. A new classification of spin adapted MRCISD states using hole-particle correspondence is suggested. The formulas and values of 244 hole loop shapes are derived according as the rule of transform from external space loop shapes to hole loop shapes. Based on the classification and the formulas for the hole loop shapes a new CI algorithm is presented and coded, which is efficient and memory saving indicated from some given examples.At appendix, the codes of calculation and fitting program are mainly presented for four-atomic systems. These fitting program may be applied to any systems including four or less than four atoms. In the code of fitting two-atomic potential energy curves some spectral constants are also calculated.更多还原