Ab initio calculations on the spectroscopic constants, vibrational levels and classical turning points for the 21∏u state of dimer 7Li2

doi:10.1088/1009-1963/16/3/021

中国物理B ›› 2007, Vol. 16 ›› Issue (3): 680-685.doi: 10.1088/1009-1963/16/3/021

Ab initio calculations on the spectroscopic constants, vibrational levels and classical turning points for the 2¹∏_u state of dimer ⁷Li₂

刘玉芳, 孙金锋, 马恒, 朱遵略

College of Physics & Information Engineering, Henan Normal University,Xinxiang 453007, China

收稿日期:2006-06-05 修回日期:2006-07-17 出版日期:2007-03-20 发布日期:2007-03-20
基金资助:
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).

Ab initio calculations on the spectroscopic constants, vibrational levels and classical turning points for the 2¹$\Pi$_u state of dimer ⁷Li₂

Liu Yu-Fang(刘玉芳)^†, Sun Jin-Feng(孙金锋), Ma Heng(马恒), and Zhu Zun-Lue(朱遵略)

College of Physics & Information Engineering, Henan Normal University,Xinxiang 453007, China

Received:2006-06-05 Revised:2006-07-17 Online:2007-03-20 Published:2007-03-20
Supported by:
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).

摘要/Abstract

摘要： The accurate dissociation energy and harmonic frequency for the highly excited 2¹\Pi_ustate 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 D_e, R_e, {\omega }_e, {\omega }_e{\chi }_e, {\alpha }_e and B_e 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\"{o}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 D_e 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 {\it ab initio} calculations of the potentials for this state.

关键词: ab initio} calculation, dissociation energy, vibrational level, turning point

Abstract: The accurate dissociation energy and harmonic frequency for the highly excited 2¹$\Pi$_ustate 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 D_e, R_e, $\omega$_e, $\omega$_e$\chi$_e, $\alpha$_e and B_e 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 D_e 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.

Key words: ab initio calculation, dissociation energy, vibrational level, turning point

中图分类号: (Ab initio calculations)

31.15.A-

31.15.vn (Electron correlation calculations for diatomic molecules) 31.50.-x (Potential energy surfaces) 33.15.Fm (Bond strengths, dissociation energies) 33.15.Mt (Rotation, vibration, and vibration-rotation constants) 33.20.Tp (Vibrational analysis)

刘玉芳, 孙金锋, 马恒, 朱遵略. Ab initio calculations on the spectroscopic constants, vibrational levels and classical turning points for the 2¹∏_u state of dimer ⁷Li₂[J]. 中国物理B, 2007, 16(3): 680-685.

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[J]. Chinese Physics, 2007, 16(3): 680-685.

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Ab initio calculations on the spectroscopic constants, vibrational levels and classical turning points for the 2¹∏_u state of dimer ⁷Li₂

Ab initio calculations on the spectroscopic constants, vibrational levels and classical turning points for the 2¹$\Pi$_u state of dimer ⁷Li₂

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