MgH分子X2Σ+，A2Π和B2Σ+电子态的势能函数

利用QCISD(T)，SAC-CI方法和cc-pVQZ，aug-cc-pVTZ，6-311++G及6-311++G(3df，2pd)基组，对MgH分子的基态X²Σ⁺，第一简并激发态A²Π和第二激发态B²Σ⁺的结构进行优化计算.通过对4个基组计算结果进行比较，得出6-311++G(3df，2pd)基组为最优基组.使用 关键词： 分子结构与势能函数 激发态 Murrell-Sorbie函数 C₆函数')" href="#">Murrell-Sorbie+C₆函数

Analytical potential energy function for the electronic states X2Σ+，A2Π and B2Σ+ of MgH molecule

The equilibrium geometries of three electronic states X²Σ⁺，A²Π and B²Σ⁺ of MgH molecule have been calculated using the SAC-CI and QCISD (T) methods with the basis sets cc-pVQZ，aug-cc-pVTZ，6-311++G and 6-311++G(3df，2pd). Comparing the above mentioned four basis sets，the conclusion is obtained that the basis set 6-311++G (3df，2pd) is the most suitable for the energy calculation of MgH molecule. The whole potential curves for three electronic states are further scanned using QCISD (T)/6-311++G (3df，2pd) method for the ground state and SAC-CI/6-311++G (3df，2pd) method for the excited states. The potential energy functions and relevant spectrum constants ω_e，ω_exe，B_e，α_e of these states are obtained by fitting to the Murrell-Sorbie function and the modified Murrell-Sorbie+C₆ function，respectively. The results showed that the spectral constants derived from the modified Murrell-Sorbie+C₆ function are in very good agreement with the experimental data，and the modified Murrell-Sorbie+C₆ function can correctly describe the potential energy function of the ground state and the first degenerate state of MgH molecule.