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以6-311++G(d,p)为基组,采用密度泛函的B3LYP方法优化得到不同外电场(-0·03—0·045a.u.)下CaS分子的基态结构参数、电偶极矩μ、电荷分布、HOMO能级、LUMO能级、能隙、红外光谱和谐振频率等.结果表明,随着正向电场的增加,分子结构与外电场有着强烈的依赖关系,且对电场方向的依赖呈现出不对称性,基态键长和分子偶极矩μ先减小后增大,在F=0·02a.u.时,键长Re取最小值0·2289nm,电偶极矩取最小值1·5969D,HOMO能级和LUMO能级处于先增大后减小,能隙始终是减小的,占据轨道的电子容易激发到空轨道.外电场对CaS分子的激发能和振子强度有较大的影响,这为进一步研究它的电致发光机理提供了一定的理论基础.
Based on the B3LYP method of density functional theory (B3LYP) with 6-311 ++ G (d, p) as a basic group, the ground state structure parameters of CaS molecules under different external electric fields (-0.03-0.045a.u.) are optimized. Dipole moment μ, charge distribution, HOMO energy level, LUMO energy level, energy gap, infrared spectrum and resonant frequency, etc. The results show that with the increase of the forward electric field, the molecular structure has a strong dependence on the external electric field, The dependence of the electric field shows an asymmetry. The bond length and molecular dipole moment μ first decrease and then increase. At F = 0.02a.u., the bond length Re takes the minimum value of 0.2289 nm. The electric dipole With the minimum value of 1 · 5969D, the HOMO and LUMO energy levels first increase and then decrease, the energy gap is always reduced, and the orbital electrons are easily excited to the empty orbit. Oscillator strength has a greater impact, which provides a theoretical basis for further study of its electroluminescence mechanism.