物理化学学报 >> 2002, Vol. 18 >> Issue (08): 737-740.doi: 10.3866/PKU.WHXB20020813

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LaH分子结构和基态势能曲线的量子化学计算

陈林红;尚仁成   

  1. 清华大学天体物理中心,北京　100084
  • 收稿日期:2001-12-10 修回日期:2002-02-25 发布日期:2002-08-15
  • 通讯作者: 陈林红 E-mail:dennychen76@sina.com

Quantum Chemical Calculation on Structure and Potential Energy Curve for the Ground State of Molecule LaH

Chen Lin-Hong;Shang Ren-Cheng   

  1. Center for Astrophysics, Tsinghua University, Beijing　100084
  • Received:2001-12-10 Revised:2002-02-25 Published:2002-08-15
  • Contact: Chen Lin-Hong E-mail:dennychen76@sina.com

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摘要： 用常规的单参考态HF、B3LYP、MPn、QCISD(T)方法在能量一致相对论有效势近似下计算了LaH分子平衡结构和基态势能曲线,考察了这些方法在计算远离平衡的金属氢合键体系势能时存在的不趋于离解极限的缺陷,提出了从B3LYP的平衡位置附近势能曲线拟合得到适用于整个空间范围的Murrell-Sorbie解析势能函数的计算方法,由此计算的振转常数和已有的实验光谱数据完全吻合.

关键词: LaH, 能量一致相对论有效核芯势, 解析势能函数, 振转光谱常数

Abstract: The equilibrium geometry and potential energy curve for the ground state of molecule LaH have been calculated on several single-reference state methods of HF,B3LYP,MPn,QCISD(T) with energy-consistent relativistic effective core potential approximation. It is found that the potential energy curves of the metal-hydrogen system, which is far from equilibrium, cannot meet the dissociation limit using almost all the above methods. A calculation method to get the global analytical potential energy function is proposed. Murrell-Sorbie analytical potential function has been derived by a nonlinear least square fitting of the data calculated at B3LYP level around the equilibrium position. The calculated spectroscopic constants from the analytical potential energy function are in good agreement with the experimental results of vibrotational spectra.

Key words: LaH, Energy-consistent relativistic effective core potentials, 　Analytical potential energy function, Vibrotational spectroscopic constants