为了研究氟化钾的物理性质，本文采用密度泛函理论和含时密度泛函理论 LSDA 方法在 6- 311G 基组水平上，研究了KF 分子在不同外加电场( -0.02 ～ 0.02 a.u.) 下的键长、能量、电荷分布、能级分布、能隙、红外光谱以及激发态的变化规律.结果表明，外加电场对 KF 分子的结构有较大影响，随着 Z( F-K 键) 方向外电场的增加，KF 分子的键长以及电偶极矩一直减小，总能量一直增大，能隙 EG 先增大后减小，同时 KF 红外光谱的最强峰发生蓝移，前 10 个激发态发生红移，另一方面，随着电场强度的增大，KF 分子解离能增大，反之解离能减小.

In order to study the physical properties of potassium fluoride，the bond length，energy，charge dis- tribution，energy level distribution，energy gap and infrared spectra of KF molecules under different applied electric fields ( -0.02 ～ 0.02 a.u.) are investigated by density functional theory LSDA method at the level of 6-311G radical group. The results display that the applied electric field has a great influence on the structure of KF molecules. With the increase of the external electric field in the direction of Z ( F-K bond) ，the bond length and electric dipole mo- ment of KF molecules have been decreased，the total energy has been increasing，and the energy gap EG has been increased first and then decreased. At the same time，the strongest peak of the KF infrared spectrum undergoes a blue shift; The first 10 excited states are

redshifted. On the other hand，as the electric field strength increases，the dissociation energy of KF molecules increases，and vice versa，the dissociation energy decreases.