关键词: LiBe^＋, 多参考组态相互作用方法, 解析势能函数, 光谱常数, 振动能级

The potential energy curves (PECs) for the ground state (X¹Σ^＋) and six low-lying excited electronic states (a³Σ^＋, b³Π, A¹Σ^＋, B¹Π, c³Σ^＋, C¹Σ^＋) of LiBe^＋ have been calculated using the muti-reference configuration interaction (MRCI＋Q) and muti-reference averaged quadratic coupled-cluster (MRAQCC) methods including Davidson correction. It is evident that states of X¹Σ^＋, a³Σ^＋, b³Π and B¹Π were weakly bound, but A¹Σ^＋, c³Σ^＋and C¹Σ^＋states were repulsive. Then the equilibrium bond length R_e for the bound states have been determined, and PECs were fitted to analytical Murrell-Sorbie potential energy function to deduce the spectroscopic constants. For the X¹Σ^＋ state, the R_e was 0.263 nm, rotation coupling constant was 316 cm^－1 and dissociation energy D_e was 0.57 eV. While for the excited states a³Σ^＋, b³Π and B¹Π states, which lay above the ground state 2.45, 3.10, 5.47 eV, corresponding w_e was 272, 236 and 257 cm^－1. A¹Σ^＋, c³Σ^＋and C¹Σ^＋were repulsive excited states when T_v were 4.75, 6.43, 6.72 eV relative to the ground state. The present results were in good agreement with other theoretical results currently available. Partial vibrational energy levels for the bound states have been determined using the Dunham expansion near the R_e.

Key words: LiBe^＋, multi-reference configuration interaction method, analytical potential energy function, spectroscopic constant, vibrational level