含非线性分子的范德华复合物的势能面和振转光谱的理论研究

This program focuses on the intermolecular potential energy surfaces (PESs) and rovibrational spectra including intramolecular vibrational excitation of some important van der Waals (vdW) complexes consisting of a rare-gas atom and a nonlinear molecule, as well as the geometries and energetics of some related vdW clusters. The unrigid monomer model will be improved by involving explicitly the dependence of one intramolecular vibrational mode in the calculations of the PESs and rovibrational spectra of vdW complexes including a nonlinear molecule. These studies can yield accurate PESs for some important systems such as Ar(or Ne，Kr)-H2O，Kr(or Xe)-C3，Xe-NH3，Ar-CH4，Xe-C6H5OH，He-C5H5N. Based on these reliable PESs, rovibrational levels and wave functions, as well as microwave and infrared spectra, such as transition frequencies, transition intensities and band origin shifts, will be interpreted and predicted in detail. With the obtained useful information, it became possible to explore the effect of the intramolecular vibrational excitation on the PESs and rovibrational spectra, and the regularity of PESs and rovibrational bound states for these vdW complexes. In addition, the geometries and energetics with cluster size will be investigated for some related vdW clusters using Genetic Algorithm.

本项目拟重点研究若干典型由稀有气体原子和非线性分子组成的范德华复合物包含分子内振动激发的分子间相互作用势能面和振转光谱，以及相关簇合物的构型和能量特征。改进非刚性单体模型，发展一种能够精确确定含非线性分子的复合物的包含分子内振动模式的势能面和光谱性质的有效理论方法。 理论研究将提供复合物Ar(或Ne，Kr)-H2O，Kr(或Xe)-C3，Xe-NH3，Ar-CH4，Xe-C6H5OH，He-C5H5N等的高精度分子间势能面，定量描述体系的几何结构，解释和预测复合物振转激发态的能级和波函数以及谱带频率、强度和谱带位移等光谱性质，分析分子内振动激发对复合物势能面和光谱性质的影响，探索并总结这类范德华复合物势能面和振转激发态的规律性，揭示分子间作用力的本质。以发展的分子间相互作用势能面为基础，采用遗传算法研究若干相关簇合物构型和能量随簇合物大小变化的特征，为实验研究提供理论依据。

在范德华复合物的高精度势能面构建和振转光谱性质及范德华簇合物构型等方面取得了重要研究成果。改进了含非线性分子的范德华复合物的振转光谱和振转激发态的非刚性单体模型，用高精度量子化学从头算方法和含键函数的大基组构建了复合物He–H2S和Ar–H2S的六维高精度分子间势能面，在分子间势能面和振转光谱计算中有效地包含了单体H2S的分子内伸缩振动和弯曲振动的影响，计算并预测了复合物振转光谱性质；改进了含线性分子的复合物的振转光谱计算模型，利用发展后的计算模型，结合高级别量子化学计算方法构建了在大气化学中有重要意义的复合物Rg−CS2 (Rg=He, Ne, Ar, Kr, Xe)和Ar−HCCH的高精度势能面，很好地解释了高分辨红外光谱实验特别是带心位移，结合不同稀有气体原子的研究结果，进一步总结了体系势能面和振转光谱性质变化的规律性；获得了由双线性分子组成的典型体系H2−HCCCN的高精度势能面，采用混合径向离散变量表象(DVR)/角度有限基组表象(FBR)方法研究了体系振转激发态的能级和波函数，很好地再现了微波光谱等光谱数据；基于构建得到的H2−HCCCN两体相互作用势，采用隐性转子模型获得p-H2−HCCCN的平均势能面，并采用遗传算法研究了簇合物(p-H2)N−HCCCN极小能量构型和能量随着簇合物大小变化的特征及规律。