采用Davidson校正的多参考组态相互作用方法(MRCI+Q)和多参考平均二次耦合团簇方法(MRAQCC)结合基组ROOS-ANO-TZP得到了LiBe+分子基态(x1∑+)以及六个低电子激发态(a3Σ+,b3∏,A1∑+,B1∏,c3∑+,C1∑+)的势能曲线(PECs).计算结果表明:X1∑+,a3∑+,b3∏和B1∏为弱束缚态,A1∑+,c3∑+和C1∑+为排斥态.接着确定出束缚态的平衡键长Re,并将得到的势能曲线在全区域拟合到Murrell-Sorbie(MS)解析势能函数形式,从而获得各束缚电子态的光谱数据.基态X1Σ+的平衡键长为0.263 nm,谐振频率ωe为316 cm-1,离解能De为0.57 eV.a3∑+,b3∏和B1∏分别位于基态2.45,3.10,5.47 eV之上,平衡核间距分别为0.297,0.270,0.284 nm,相应的谐振频率为272,236和257 cm-1.排斥态A1∑+,c3∑+和C1∑+对应的垂直激发能Tv分别为4.75,6.43,6.72 eV.目前计算值和文献结果符合得非常好.最后在束缚态的平衡结构附近做Dunham展开,获得的光谱常数与MS结果一致,据此得到x1∑+,a3∑+,b3∏和B1∏态的部分振动能级.%The potential energy curves (PECs) for the ground state (X1Σ+) and six low-lying excited electronic states (a3Σ+, b3∏, A1Σ+, B1∏, 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+, b3∏ and B1∏ were weakly bound, but A1Σ+, c3Σ+and C1Σ+states were repulsive. Then the equilibrium bond length Re 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 Re was 0.263 nm, rotation coupling constant was 316 cm-1 and dissociation energy De was 0.57 eV. While for the excited states a3Σ+, b3∏ and B1∏ states,which lay above the ground state 2.45, 3.10, 5.47 eV, corresponding we was 272, 236 and 257 cm-1. A1Σ+,c3Σ+ and C1Σ+were repulsive excited states when Tv 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 Re.
展开▼
