中文摘要：

使用内收缩多参考组态相互作用方法和相关一致基aug-cc-pVnZ （n ＝Q，5）对BeO分子的光谱性质开展研究。计算了BeO分子X1Σ＋， a3Π和b3Σ＋态的势能曲线，并将3个态的能量外推至完全基组极限。对分子能量进行相对论效应及核价相关效应修正计算。相对论修正计算采用cc-pV5 Z相对论收缩基，核价相关修正计算使用的基组是aug-cc-pCVQZ基。拟合能量修正的外推势能曲线，得到3个态的光谱常数（ Te ， Re ，ωe，ωexe， Be，αe和De）。这些结果与实验结果符合很好。详细讨论了基组、核价相关修正和相对论修正对BeO分子的能量及光谱常数的影响。通过求解双原子分子核运动的振－转Schr？dinger方程，找到了J ＝0时BeO分子3个态的全部振动态及与每一振动态对应的振动能级和惯性转动常数等分子常数。它们与实验结果一致。

英文摘要：

The highly accurate internally contracted multireference configuration interaction method with the David -son modification （MRCI＋Q） was employed to calculate the potential energy curves （PECs） of the X1Σ＋, a3Πand b3Σ＋electronic states of the BeO molecule.The Dunning’s correlation-consistent basis sets, aug-cc-pV5Z and aug-cc-pVQZ, were used.The effects on the PEC by the core-valence correlation and relativistic corrections were taken into account .The relativistic correction calculations were made using the third-order Douglas-Kroll Hamiltonian approxima-tion at the level of a cc-pV5Z-DK basis set.The core-valence correlation corrections were calculated with an aug-cc-pCVQZ basis set.With the PECs obtained, the spectroscopic parameters （Te, Re,ωe,ωexe, Be,αe and De） of each state were determined .On the whole , the most accurate spectroscopic parameters of BeO molecule were determined . Based on these PECs , the whole vibrational states of each state of the non-rotating BeO molecule were computed by nu-merically solving the radial Schr？dinger equation of nuclear motion .The vibrational levels and inertial rotation constants were determined when J =0.Comparison with the available experimental data and other theories showed that the pres -ent spectroscopic parameters and molecular constants were more accurate and complete .