中国物理B ›› 2006, Vol. 15 ›› Issue (5): 1015-1021.doi: 10.1088/1009-1963/15/5/025

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Ab initio calculation of accurate dissociation energy, potential energy curve and dipole moment function for the A1∑ + state 7LiH molecule

施德恒1, 刘玉芳2, 孙金锋3, 朱遵略3, 杨向东4   

  1. (1)College of Physics & Electronic Engineering, Xinyang Normal University, Xinyang 464000, China;College of Physics & Information Engineering, Henan Normal University, Xinxiang 453007, China;Institute of Atomic and Molecular Physics, Sichuan University,Cheng; (2)College of Physics & Information Engineering, Henan Normal University, Xinxiang 453007, China; (3)College of Physics & Information Engineering, Henan Normal University, Xinxiang 453007, China;Institute of Atomic and Molecular Physics, Sichuan University,Chengdu 610065, China; (4)Institute of Atomic and Molecular Physics, Sichuan University,Chengdu 610065, China
  • 收稿日期:2005-09-02 修回日期:2005-10-29 出版日期:2006-05-20 发布日期:2006-05-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No 10174019), the Natural Science Foundation of Henan Province, China (Grant No 2006140008) and Henan Innovation for University Prominent Research Talents (Grant No 2006KYCX002).

Ab initio calculation of accurate dissociation energy, potential energy curve and dipole moment function for the A1∑ + state 7LiH molecule

Shi De-Heng (施德恒)abc, Liu Yu-Fang (刘玉芳)b, Sun Jin-Feng (孙金锋)bc, Yang Xiang-Dong (杨向东)c, Zhu Zun-Lue (朱遵略)bc   

  1. a College of Physics & Electronic Engineering, Xinyang Normal University, Xinyang 464000, Chinab College of Physics & Information Engineering, Henan Normal University, Xinxiang 453007, China; c Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
  • Received:2005-09-02 Revised:2005-10-29 Online:2006-05-20 Published:2006-05-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No 10174019), the Natural Science Foundation of Henan Province, China (Grant No 2006140008) and Henan Innovation for University Prominent Research Talents (Grant No 2006KYCX002).

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摘要： The reasonable dissociation limit of the A1∑+ state $^{7}$LiH molecule is obtained. The accurate dissociation energy and the equilibrium geometry of this state are calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space for the first time. The whole potential energy curve and the dipole moment function for theA1∑+ state are calculated over a wide internuclear separation range from about 0.1 to 1.4\,nm. The calculated equilibrium geometry and dissociation energy of this potential energy curve are of R_{\e}=0.2487\,nm and D_{\e}=1.064\,eV, respectively. The unusual negative values of the anharmonicity constant and the vibration-rotational coupling constant are of \textit{\omega }_{\e}\textit{\chi }_{\e}=--4.7158cm^{ - 1} and \textit{\alpha }_{\e}=--0.08649cm^{ -1}, respectively. The vertical excitation energy from the ground to the A1∑+ state is calculated and the value is of 3.613\,eV at 0.15875nm (the equilibrium position of the ground state). The highly anomalous shape of this potential energy curve, which is exceptionally flat over a wide radial range around the equilibrium position, is discussed in detail. The harmonic frequency value of 502.47cm1 about this state is approximately estimated. Careful comparison of the theoretical determinations with those obtained by previous theories about the A1∑+ state dissociation energy clearly shows that the present calculations are much closer to the experiments than previous theories, thus represents an improvement.

关键词: ab initio calculation, dissociation energy, dipole moment, potential energy curve

Abstract: The reasonable dissociation limit of the A1∑+ state $^{7}$LiH molecule is obtained. The accurate dissociation energy and the equilibrium geometry of this state are calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space for the first time. The whole potential energy curve and the dipole moment function for the A1∑+ state are calculated over a wide internuclear separation range from about 0.1 to 1.4 nm. The calculated equilibrium geometry and dissociation energy of this potential energy curve are of Re=0.2487 nm and De=1.064 eV, respectively. The unusual negative values of the anharmonicity constant and the vibration-rotational coupling constant are of  $\omega_{\rm e}\chi_{\rm e}$ =-4.7158cm-1 and $\alpha_{\rm e}$=-0.08649cm-1, respectively. The vertical excitation energy from the ground to the A1∑+ state is calculated and the value is of 3.613 eV at 0.15875nm (the equilibrium position of the ground state). The highly anomalous shape of this potential energy curve, which is exceptionally flat over a wide radial range around the equilibrium position, is discussed in detail. The harmonic frequency value of 502.47cm1 about this state is approximately estimated. Careful comparison of the theoretical determinations with those obtained by previous theories about the A1∑+ state dissociation energy clearly shows that the present calculations are much closer to the experiments than previous theories, thus represents an improvement.

Key words: ab initio calculation, dissociation energy, dipole moment, potential energy curve

中图分类号:  (Bond strengths, dissociation energies)

  • 33.15.Fm
31.50.-x (Potential energy surfaces) 33.15.Bh (General molecular conformation and symmetry; stereochemistry) 33.15.Kr (Electric and magnetic moments (and derivatives), polarizability, and magnetic susceptibility) 33.15.Mt (Rotation, vibration, and vibration-rotation constants)