Theoretical investigations on analytical potential energy function and spectroscopic parameters for the state b3Πu of dimer 7Li2.

The SAC-CI (symmetry-adapted-cluster configuration-interaction) method presented in Gaussian 03 program package is applied to investigate the adiabatic potential energy curves (PECs) of 7Li2(b3Πu). These calculations are performed at numbers of basis sets, such as 6-311++G(3df,3pd), 6-311++G(2df,2pd), 6-311++G(df,pd), D95V++, D95(3df,3pd), D95(d,p), cc-PVTZ, 6-311++G and 6-311++G(d,p). All the ab initio calculated points are fitted to the analytic Murrell-Sorbie functions and then used to compute the spectroscopic parameters. The analytic potential energy function (APEF) for this b3Πu state is reported. By comparison, the spectroscopic parameters reproduced by the APEF attained at 6-311++G(2df,2pd) are found to be very close to the latest experimental findings. With the APEF obtained at the SAC-CI/6-311++G(2df,2pd) level of theory, a total of 62 vibrational states is found when J = 0. The complete vibrational levels, classical turning points, inertial rotation and centrifugal distortion constants for these vibrational states are also reported. The reasonable dissociation limit for this state is deduced using the calculated results at present. © 2007 Wiley Periodicals, Inc. Int J Quantum Chem, 2007 [ABSTRACT FROM AUTHOR]