Acta Phys. -Chim. Sin. ›› 2002, Vol. 18 ›› Issue (08): 737-740.doi: 10.3866/PKU.WHXB20020813

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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

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