~7Li_2分子2 ~3Π_u激发态的解析势能函数、振动能级及其转动惯量

Investigation of analytic potential energy function,vibrational levels and inertial rotation constants for the 2 ~3Π_u state of spin-aligned dimer ~7Li_2

使用Gaussian03程序包中的“对称性匹配簇-组态相互作用”方法、在0.13—2.0nm的核间距范围内利用6-311++G(d,p)基组对7Li2(23Πu)分子的势能曲线进行了计算,同时使用最小二乘法将计算结果拟合成了解析势能函数.利用拟合出的解析势能函数并结合Rydberg-Klein-Rees方法,计算了该态的谐振频率,进而计算了该态的其他光谱常数,分别为Te=3.6701eV,De=1.0764eV,Re=0.3000nm,ωe=285.69cm-1,ωeχe=1.8351cm-1,αe=0.00942cm-1和Be=0.5340cm-1,其中光谱常数Te,De,Re和ωe的值与文献值相符很好.以得到的解析势能函数为基础,通过求解双原子分子核运动的径向Schr dinger方程,发现J=0时7Li2(23Πu)分子存在67个振动态,求出了相应于每一振动态的振动能级、振动经典转折点及转动惯量.

Using the symmetry-adapted-cluster-configuration-interaction （SAC-CI） method provided by the Gaussian 03 program package, the potential energy curve for ^7Li2 （2^3Ⅱu） has been calculated with the basis set 6-311＋＋ G（d,p） over the internuclear separation range from 0.13 to 2.0 nm. And the ab initio calculated points have been subjected to a least squares fitting to Murrell-Sorbie function. Employing the Rydberg-Klein-Rees method, the harmonic frequency is derived from the analytic potential energy function and then other spectroscopic data are further computed. These spectroscopic data are Te = 3.6701 eV, De = 1.0764 eV, Re = 0.3000 nm, ωe = 285.69 cm^-1 , ωeXe = 1.8351 cm^-1, αe = 0.00942 cm^-1 and Be = 0.5340 cm^-1, respectively. In particular, the present Te, De, Re and ωe values are in excellent agreement with other theoretical results. With the analytic potential energy function obtained on the SAC-CI/6-311 ＋ ＋ G（d, p） level, a total number of 67 vibrational states for the 2^3Ⅱu state is found when J = 0 by solving the radial Schrǒdinger equation of nuclear motion. The complete vibrational levels, classical turning points and inertial rotation constants for these vibrational states are also reported. The reasonable dissociation limit for the 2^3Ⅱu state is deduced using the present results calculated.