BeH,H2和BeH2的分子结构和势能函数

Structure and analytic potential energy function of the molecules BeH,H_2 and BeH_2

用二次组态相关(QCISD)和密度泛函(B3LYP)方法,选用6-311++g(d,p),6-311++g(3df,3pd)和D95(3df,3pd)基组对H2,BeH和BeH2分子的结构进行优化.得到它们的基态电子态分别为H2(1Σg),BeH(2Σ)和BeH2(1Σg),BeH2分子的稳定构型为D∞h构型.采用最小二乘法拟合出BeH和H2分子的8参数Murrell-Sorbie函数,在此基础上推导出光谱数据和力常数;由多体项展式理论导出BeH2分子的分析势能函数.H+BeH生成BeH2(D∞h)分子存在较深的势阱,容易生成H-Be-H络合物分子.反应Be+H2→HBeH,ΔH=-1.4654eV,是放热反应.

Quadratic configuration interaction calculation（QCISD） and B3LYP methods have been used to optimize the possible ground-state structures of H2,BeH and BeH2 molecules.The results show that their ground electronic states are H2（1Σg）,BeH（2Σ） and BeH2（1Σg）,the stable structure of BeH2 molecule is of D∞h symmetry.The Murrell-Sorbie potential energy function with 8 parameters of BeH and H2 molecule has been derived from the least square method,according to which spectral data and force constants are deduced.The analytical potential energy function of BeH2 is derived from the many-body expansion theory.Since BeH2（D∞h） formed from H＋BeH has a deep potential trap,the complex com pound molecule of H-Be-H is easily formed.The reaction of Be＋H2→HBeH with ΔH=-1.4654 eV is an exothermic reaction.