Abstract The accurate dissociation energy and harmonic frequency for the highly excited 21$\Pi$u state of dimer 7Li2 have been calculated using a symmetry-adapted-cluster configuration-interaction method in complete active space. The calculated results are in excellent agreement with experimental measurements. The potential energy curves at numerous basis sets for this state are obtained over a wide internuclear separation range from about 2.4a0 to 37.0a0. And the conclusion is gained that the basis set 6-311++G(d,p) is a most suitable one. The calculated spectroscopic constants De, Re, $\omega$e, $\omega$e$\chi$e, $\alpha$e and Be at 6-311++G(d,p) are 0.9670 eV, 0.3125 nm, 238.6 cm-1, 1.3705 cm-1, 0.0039 cm-1 and 0.4921 cm-1, respectively. The vibrational levels are calculated by solving the radial Schr?dinger equation of nuclear motion. A total of 53 vibrational levels are found and reported for the first time. The classical turning points have been computed. Comparing with the measurements, in which only the first nine vibrational levels have been obtained so far, the present calculations are very encouraging. A careful comparison of the present results of the parameters De and $\omega$e with those obtained from previous theories clearly shows that the present calculations are much closer to the measurements than previous theoretical results, thus representing an improvement on the accuracy of the ab initio calculations of the potentials for this state.
Received: 05 June 2006
Revised: 17 July 2006
Accepted manuscript online:
Fund: Project supported by the National Natural
Science Foundation of China (Grant No~10574039) and Henan Innovation for
University Prominent Research Talents of China (Grant No~2006KYCX002).
Cite this article:
Liu Yu-Fang(刘玉芳), Sun Jin-Feng(孙金锋), Ma Heng(马恒), and Zhu Zun-Lue(朱遵略) Ab initio calculations on the spectroscopic constants, vibrational levels and classical turning points for the 21$\Pi$u state of dimer 7Li2 2007 Chinese Physics 16 680
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