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Ab initio calculations on the a3∑+u state properties of dimer 7Li2
施德恒, 孙金锋, 朱遵略, 刘玉芳
2007 (9):
2701-2708.
doi: 10.1088/1009-1963/16/9/034
摘要
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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.
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