MgO在外电场作用下的分子特性研究

Study on the molecular properties of MgO in the external electric field

在不同理论水平优化得到MgO分子的基态稳定构型,通过与实验值的比较,选取密度泛函B3LYP方法和6-311++g(d,p)基组对MgO在不同外电场(—0.015,—0.010,—0.005,0.005,0.010,0.015 a.u.)下分子基态的稳定电子结构进行计算,研究了外电场对MgO分子基态总能量、键长、偶极矩、能级分布、能隙、电荷分布及红外光谱的影响。结果表明,随着Mg→O方向外电场的增加,分子键长、偶极矩和能隙递减,原子电荷也递减,总能量升高,频率及其红外强度递增;在外电场作用下,MgO基态分子势能曲线升高,离解能减小。

The equilibrium structure of the ground state of MgO molecule are computea at various theoretical level. Compared with the experimental values, the DFT-B3LYP method and 6-311＋＋g（d, p） basis set are used to optimize the geometric structure of the ground state of MgO molecule in electric fields ranging from -0.015 to 0. 015 a. u.. The effects of electric fields on the system energy, bond distance, dipole moment, energy levels, HOMO-LUMO gaps, charge distribution and the infrared spectrum for the ground states of MgO molecule are studied. The results show that the molecular bond distance, dipole moment, HOMO-LUMO gaps and the total atomic charges gradually decrease and the energy, frequence and IR intensity gradually increase as the increase of the external electric field along the molecular axis Mg -O. At the same time,the potential energy curve of the ground states （X^1 ∑＋ ） of MgO molecule rise and the dissociation energy decrease in the external electric field.