外电场下PH分子特性和势能函数

The molecular characteristics and potential energy of PH under external field

摘要:

采用密度泛函B3P86和单双取代耦合团簇CCSD(T)/cc-PV5Z方法，结合Dunning相关一致五重基cc-PV5Z优化计算外加不同电场下的PH分子结构，同时扫描单点能，获得不同外电场作用下的平衡几何键长、偶极矩、振动频率、红外光谱和势能曲线. 结果分析表明，当外加电场时PH分子的物理性质参数和势能曲线都发生了较大变化，且外加反向电场时变化幅度更明显. 为了分析外电场效应，本文引入偶极近似理论，构建外电场作用下的势能函数模型，同时编制程序拟合不同外电场下的势能函数，得到拟合参数，进而分析计算临界离解电场参量. 结果与数值计算和理论分析较为一致，误差都在2%以内，说明构建的势模型用来研究外电场效应是合理和可靠的. 这为进一步分析PH分子在外电场中分子光谱、动力学特性和Stark效应冷却囚禁提供重要的理论参考.

关键词:PH分子;势能函数模型;外电场

Abstract:

By setting different electric fields and adopting density functional B3P86 and high precision coupled cluster CCSD (T) method, combining with relevant agreement Dunning five heavy cc-PV5Z, the geometric structure of PH molecule is optimized and the single point energies are scanned. The bond lengths, dipole moments, vibration frequencies, infrared spectrum and potential energy curves are obtained. The results show that the physical properties parameters and the potential energy values will change with the change of external electric field, especially at reverse direction electric field. In order to analyze the external field effect and get the critical dissociation electric parameter, the dipole approximation is adopted to construct potential model, then the model is put to fit the corresponding potential energy curve of external electric field. It is found that the fitted critical dissociation electric parameter is reasonably consistent with the numerical calculation; i.e., the relative errors are also less than 2%. So the constructed model is reliable and accurate for analyzing the external field effect. These will provide important theoretical and experimental reference for the studies of molecular spectroscopy, dynamics and molecular cooling with Stark effect.

Key words:PH molecule; Potential function model; External field