外电场对BeH分子结构和势能函数的影响

摘要

Adopting density functional B 3P86/cc-PV5Z method and setting different electric fields , the geo-metric structures of BeH molecule are optimized , and the bond lengths , dipole moments , vibration frequencies and other physical properties parameters are obtained.On the basis of setting appropriate parameters and adop-ting the energy of high precision coupled cluster CCSD ( T) method to scan single point energies , the potential energy curves under different external fields are given.The results show that the physical properties parameters and potential energy values will change with the external electric field change , especially at reverse direction e-lectric fields.In order to 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 consistent with numerical calculation , and so the constructed model is reliable and accurate.These will provide important theoretical and experimental reference for studying the molecular spectroscopy , dynamics and molecular cooling with Stark effect.%采用密度泛函B3P86方法，结合Dunning的相关一致五重基cc－PV5Z，设置不同的外电场参量进行优化计算，获得了不同外电场下BeH分子的键长、偶极矩、振动频率和红外光谱等物理性质参数。通过分析参数随外电场的变化关系，判断离解电场所处的范围，设置合适的外电场参数，采用单双取代耦合团簇CCSD（ T）方法，扫描计算该范围的单点能获得其势能曲线。结果分析表明物理性质参数和势能随外电场的变化而变化，且外加反向电场时变化幅度更大。采用偶极近似构建外电场下的势能函数模型，编制程序拟合对应的势能函数，得出拟合参数，进而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，说明构建的模型是合理和可靠的。这为分析外场下分子光谱、动力学特性和分子Stark效应冷却囚禁提供重要的理论和实验参考。