中国物理B ›› 2007, Vol. 16 ›› Issue (9): 2701-2708.doi: 10.1088/1009-1963/16/9/034

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Ab initio calculations on the a3∑+u state properties of dimer 7Li2

施德恒1, 孙金锋2, 朱遵略2, 刘玉芳2   

  1. (1)College of Physics {\& Electronic Engineering, Xinyang Normal University, Xinyang 464000, China;College of Physics {\& Information Engineering, Henan Normal University, Xinxiang 453007, China; (2)College of Physics {\& Information Engineering, Henan Normal University, Xinxiang 453007, China
  • 收稿日期:2006-09-06 修回日期:2007-03-11 出版日期:2007-09-20 发布日期:2007-09-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant No~10574039) and the Natural Science Foundation of Henan Province, China (Grant No~2006140008 and 2007140015).

Ab initio calculations on the a3∑+u state properties of dimer 7Li2

Shi De-Heng(施德恒)a) b)† , Sun Jin-Feng(孙金锋)b), Zhu Zun-Lue(朱遵略)b), and Liu Yu-Fang(刘玉芳)b)   

  1. a College of Physics & Electronic Engineering, Xinyang Normal University, Xinyang 464000, China; b College of Physics & Information Engineering, Henan Normal University, Xinxiang 453007, China
  • Received:2006-09-06 Revised:2007-03-11 Online:2007-09-20 Published:2007-09-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant No~10574039) and the Natural Science Foundation of Henan Province, China (Grant No~2006140008 and 2007140015).

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摘要： The comparison between single-point energy scanning (SPES) and geometry optimization (OPT) in determining the equilibrium geometry of the $a^{3}\Sigma ^{ + }_{\rm u}$ state for $^{7}$Li$_{2}$ is made at numerous basis sets such as 6-311++G(2df), cc-PVTZ, 6-311++G(2df,p), 6-311G(3df,3pd), 6-311++G(2df,2pd), D95(3df,3pd), 6-311++G, DGDZVP, 6-311++G(3df,2pd), 6-311G(2df,2pd), D95V++, CEP-121G, 6-311++G(d,p), 6-311++G(2df,pd) and 6-311++G(3df,3pd) in full active space using a symmetry-adapted-cluster/ symmetry-adapted-cluster configuration-interaction (SAC/SAC-CI) method presented in Gaussian03 program package. The difference of the equilibrium geometries obtained by SPES and by OPT is reported. Analyses show that the results obtained by SPES are more reasonable than those obtained by OPT. We have calculated the complete potential energy curves at these sets over a wide internuclear distance range from about 3.0$a_{0}$ to 37.0$a_{0}$, and the conclusion is that the basis set cc-PVTZ is the most suitable one. With the potential obtained at cc-PVTZ, the spectroscopic data ($T_{\rm e}$, $D_{\rm e}$, $D_{0}$, $\omega _{\rm e },\omega _{\rm e}\chi _{\rm e}$, $\alpha _{\rm e}$ and $B_{\rm e})$ are computed and they are 1.006 eV, 338.71~cm$^{ - 1}$, 307.12 cm$^{ - 1}$, 64.88 cm$^{ - 1}$, 3.41 cm$^{ - 1}$, 0.0187 cm$^{ - 1}$ and 0.279 cm$^{ - 1}$, respectively, which are in good agreement with recent measurements. The total 11 vibrational states are found at $J$=0. Their corresponding vibrational levels and classical turning points are computed and compared with available RKR data, and good agreement is found. One inertial rotation constant ($B_{\upsilon })$ and six centrifugal distortion constants ($D_{\upsilon }$ $H_{\upsilon }$, $L_{\upsilon }$, $M_{\upsilon }$, $N_{\upsilon }$ and $O_{\upsilon })$ are calculated. The scattering length is calculated to be --27.138$a_{0}$, which is in good accord with the experimental data.

关键词: ab initio}, potential energy curve, spectroscopic data, vibrational state, scattering length

Abstract: The comparison between single-point energy scanning (SPES) and geometry optimization (OPT) in determining the equilibrium geometry of the $a^{3}\Sigma ^{ + }_{\rm u}$ state for $^{7}$Li$_{2}$ is made at numerous basis sets such as 6-311++G(2df), cc-PVTZ, 6-311++G(2df,p), 6-311G(3df,3pd), 6-311++G(2df,2pd), D95(3df,3pd), 6-311++G, DGDZVP, 6-311++G(3df,2pd), 6-311G(2df,2pd), D95V++, CEP-121G, 6-311++G(d,p), 6-311++G(2df,pd) and 6-311++G(3df,3pd) in full active space using a symmetry-adapted-cluster/ symmetry-adapted-cluster configuration-interaction (SAC/SAC-CI) method presented in Gaussian03 program package. The difference of the equilibrium geometries obtained by SPES and by OPT is reported. Analyses show that the results obtained by SPES are more reasonable than those obtained by OPT. We have calculated the complete potential energy curves at these sets over a wide internuclear distance range from about 3.0$a_{0}$ to 37.0$a_{0}$, and the conclusion is that the basis set cc-PVTZ is the most suitable one. With the potential obtained at cc-PVTZ, the spectroscopic data ($T_{\rm e}$, $D_{\rm e}$, $D_{0}$, $\omega _{\rm e },\omega _{\rm e}\chi _{\rm e}$, $\alpha _{\rm e}$ and $B_{\rm e})$ are computed and they are 1.006 eV, 338.71 cm$^{ - 1}$, 307.12 cm$^{ - 1}$, 64.88 cm$^{ - 1}$, 3.41 cm$^{ - 1}$, 0.0187 cm$^{ - 1}$ and 0.279 cm$^{ - 1}$, respectively, which are in good agreement with recent measurements. The total 11 vibrational states are found at $J$=0. Their corresponding vibrational levels and classical turning points are computed and compared with available RKR data, and good agreement is found. One inertial rotation constant ($B_{\upsilon })$ and six centrifugal distortion constants ($D_{\upsilon }$ $H_{\upsilon }$, $L_{\upsilon }$, $M_{\upsilon }$, $N_{\upsilon }$ and $O_{\upsilon })$ are calculated. The scattering length is calculated to be --27.138$a_{0}$, which is in good accord with the experimental data.

Key words: ab initio, potential energy curve, spectroscopic data, vibrational state, scattering length

中图分类号:  (Spectroscopy and geometrical structure of clusters)

  • 36.40.Mr
31.15.A- (Ab initio calculations) 31.50.-x (Potential energy surfaces) 33.15.Bh (General molecular conformation and symmetry; stereochemistry) 33.15.Mt (Rotation, vibration, and vibration-rotation constants) 33.20.Tp (Vibrational analysis)