【作者】 徐定国；

【导师】 谢代前；

【作者基本信息】 四川大学 ， 物理化学， 2003， 博士

【摘要】 用量子力学递推方法研究分子光谱和动力学已成为当今理论化学研究的重要趋势之一。本文以HCN和HCCH为例，利用两种基于Krylov子空间的量子递推方法（Lanczos和Chebyshev）和高精度量子化学计算方法研究了它们的分子光谱和动力学性质。 对于HCN分子，我们用高级别从头算得到了最低的两个单重激发态的势能面和跃迁偶极矩，并以此为基础研究了在这两个态上的共振态光谱和预离解动力学。计算表明，在HCN第一吸收谱带的预离解中以基态的CN产物为主，而转动分布则显示出大的振荡。研究还表明，对于DCN分子的光分解动力学，其吸收光谱中振动能级呈簇状出现。Fermi共振对于HCN/DCN在其最低的两个吸收光谱上的离解起着非常重要的作用，并使得我们将第二吸收光谱带重新指认为1¹A″电子态。 在Lanczos算法的基础上，我们采用量子力学全维计算得到了在两个已知的势能面上HCCH分子13000cm^-1以下的收敛的能级。另外我们用改良的SLP方法计算了HCCH分子的共振发射光谱，并用设计的目标函数对其高振动激发态进行了指认，在理论上毫无疑问地确认了该分子在7000～10000cm^-1左右存在正则模向局域模跃迁这一现象。更多还原

【Abstract】 Quantum recursive methods have been one of the major trends in studying molecular spectroscopy and dynamics in current theoretical chemical research. In this work, we used two Krylov subspace based methods (Lanczos and Chebyshev) to study the spectroscopy and dynamics of HCN and HCCH molecules.For HCN molecule, we obtained the potential energy surfaces and transition dipole moments for its two lowest excited electronic singlet states using high-level ab initio calculations. Based on these information, we studied the resonance spectra and predissociation dynamics on these two states. For the first absorption band, the CN radical is found to be predominantly in its ground vibrational state, while the rotational distribution is of highly oscillatory structure. On the other hand, the absorption spectrum of DCN has a feature of clustering of resonance states. We also found that Fermi resonance plays an important role in the predissociation dynamics for the first two absorption bands. Accordingly, the beta band is reassigned to its 11An state.Using a modified SLP method, we calculated the resonance emission spectra of acetylene from several vibrational states of the excited A state. The calculation is performed with a full dimensional quantum method, and the converged vibrational levels are obtained and assigned up to 13000 cm-1. In addition, using some artificial spectra, we identified that the normal-to-local mode transition in bending mode will occur around 7000 ~ 10000 cm-1, in excellent agreement with the experimental observations.更多还原