PO分子在外电场下的特性研究

On the Properties of PO Molecule under the External Electric Field

以6-311G(3df)为基组,采用B3LYP方法研究PO分子在不同外电场(-0.04~0.04 a.u.)下的基态参数、总能量、偶极矩、电荷分布、HOMO能级、LUMO能级和能隙,在优化构型的基础上,使用相同的基组和同等强度的外电场,采用CIS-DFT方法研究PO分子前9个激发态能量、激发波长和振子强度.结果表明:PO分子的几何参数随电场强度变化明显.电场由-0.04变化至0.04 a.u.时,体系的总能量先增加后减少;偶极矩不断减小;HOMO能级和LUMO能级受外电场的影响并不明显,但α电子和β电子的能级数值差别较大,二者的能隙随外电场强度的增加呈相反的两种变化.激发态的激发能、跃迁波长电场变化明显,而外电场并没有改变电子的跃迁特性.

A density functional method(B3LYP)with 6-311G(3df)basis sets has been used to study the equilibrium geometric parameters,total energies,dipole moments,charge distributions,the highest occupied molecular orbital(HOMO)energies,the lowest unoccupied molecular orbital(LUMO)energies,and energy gaps of PO molecule under different external electric field ranging from-0.04 to 0.04 a.u.On the basis of optimized configuration,the excitation energy,transition wavelength and oscillator strength of the first nine excited states in the same intense external electric field and basis sets are calculated by the configuration interaction singles(CIS-B3LYP)method.The results show that the geometric parameters of PO molecule strongly depend on the magnitude and direction of external electric field.When the electric field changes from-0.04 a.u.to 0.04 a.u.,the total energy of the system first increases and then decreases;the dipole moment decreases continuously;the influence of external electric field on homo level and LUMO energy level is not obvious,but the energy level values of α-electron and β-electron are quite different,and their energy gap shows two opposite changes with the increase of external electric field.The excitation energy and transition wavelength of the excited state change obviously,but the external electric field does not change the transition characteristics of the electron.