(ZnSe)_(12)在外电场下的基态性质和激发特性研究

以SBKJC为基组,采用密度泛函PBE0方法研究了不同外电场(0-0.030 a.u.)对(ZnSe)_(12)的基态几何结构、电荷分布、能量、电偶极矩、能隙、最小振动频率的影响;继而采用含时的TD-PBE0方法研究了(ZnSe)_(12)在外电场下的激发特性,并模拟了紫外-可见光谱.研究结果表明:外电场的加入导致分子对称性降低,当电场从0 a.u.变化到0.030 a.u.时,偶极矩逐渐增加,体系总能量、最小谐振频率和能隙一直减小.外电场对(ZnSe)_(12)的激发特性影响较大,随着电场的增加,紫外-可见光谱发生红移,同时对振子强度有很大影响,原来振子强度不为零的激发态变弱或成为禁阻跃迁,而原来振子强度很弱或禁阻的激发态变得很强.可以通过改变外电场来改变(ZnSe)_(12)的基态性质,以及控制(ZnSe)_(12)的吸收和发光特性.

Ground state properties and excitation properties of (ZnSe)12 under different external electric fields

In this work, density functional theory method at the PBE0 level with SBKJC basis set was used to calculate the ground state structure, natural charges distribution, energy gap, electric dipole moment, lowest harmonic frequency of (ZnSe)12 under different external electric fields (0-0.030 a.u.). The excitation properties (containing excited energy, excited wavelength and oscillator strength) of (ZnSe)12 were calculated by the time-dependent density functional theory method (TD-PBE0), and the UV-Vis spectra were simulated. The results show that (ZnSe)12 can be elongated in the direction of electric field. Meanwhile, the addition of external electric field results in lower symmetry (C2v). Moreover, the electric dipole moment is proved to be increasing with the increase of external field, but the total energy, lowest harmonic frequency and energy gap are proved to decrease with the increase of external field. Furthermore, the external electric field has significant effects on the excitation properties of (ZnSe)12. The increase of the electric field can lead to the redshift of UV-Vis spectra. With the change of the electric field, the strong excited state (with big oscillator strength) can become very weak (with small oscillator strength) or optically inactive (with the oscillator strength of zero). Meanwhile, the weak excited state can become the strong excited state by the external field. The ground state properties and excitation properties of (ZnSe)12 can be modified by the external electric field.