外电场对2-氟-5-溴吡啶分子结构与电子光谱影响的研究

采用密度泛函B3LYP方法,在6-311++g(3df,3pd)基组水平上优化了不同外电场下2-氟-5-溴吡啶分子的基态稳定构型、电偶极矩和分子的总能量,在此基础上利用杂化CIS方法研究了外电场下2-氟-5-溴吡啶分子的前9个激发态的激发能、波长和振子强度受外电场的影响规律.结果表明:5C-9Br和3C-10F间键长受到X轴向外场影响最大,随着外电场的继续增加,可能最先趋于断裂;在外电场F=-0.05 a.u.时总能量达到最大,而偶极矩达到最小;LUMO能级受外场影响较大,HOMO能级受外电场影响较小;激发波长、振子强度也受外电场影响,但随电场变化比较复杂.

Influence of external electric field on the molecular structure and electronic spectrum of 2-fluoro-5-bromopyridine molecule

The B3LYP method of density functional theory (DFT) at 6-311++g(3df,3pd) level is used to calculate the geometrical parameters, dipole moments and total energies of the ground state of 2-fluoro 5-bromopyridine molecule under different external electric fields in this paper. On the basis of this, the single-excitation configuration interaction (CIS) is used to study the influences of external electric field on the excited wavelengths and oscillators of the first nine excited states. The results show that the bond lengths (5C-9Br, 3C-10F) will be greatest impact by X axial electric field, and with the continue increase of electric field, they may be the first to break. When the external electric field F=0.005 a.u., the total energy is maximum, and the dipole moment is minimized. The LUMO energy levels are greatly influenced by external electric field, but the HOMO energy levels are less affected by the external electric field. The excited wavelength and oscillator are influenced by electric field, but their changes with the electric field are relatively complex.