基于密度泛函理论的外电场下c-C4F8的结构及其特性

采用密度泛函理论CAM-B3LYP/DGDZVP2对c-C4F8进行优化计算,得到基态分子结构.在该结构基础上施加线性外电场(0~10.284 V·pm^-1),获得了c-C4F8的几何特性、能量、前线轨道能级、键能和红外光谱数据.结果表明:当电场沿x轴变大时,c-C4F8的点群从D2d变为C1,偶极矩和极化率不断增大,结构稳定性降低;分子总能量和能隙不断减小,且C(4)-F(10)键的键能降低速度最快,最有可能率先在外电场作用下断裂,导致c-C4F8结构和对称性被破坏.同时c-C4F8的绝热电子亲和能单调上升,分子吸收自由电子的能力增强;红外光谱中,吸收峰的个数增加,4个主要吸收峰发生了红移.

Structure and properties of perfluorocyclobutane under external electric field based on density functional theory

Optimization of the perfluorocyclobutane(c-C4F8)is conducted in order to obtain a stable ground state via the density functional theory at the CAM-B3 LYP/DGDZVP2 level.When the linear external electric field(0~10.284 V·pm^-1)is applied,the geometric characteristics,energy,frontier orbital energy level,bond energy and infrared spectrum of c-C4F8 were obtained.The conclusions show that the symmetry of c-C4F8 is gradually destroyed,point group changed from D2d to C1,and the increase of dipole moment and polarizability leads to the instability of c-C4F8 when the electric field increases along the x-axis,the total energy and energy gap decrease continuously.The bond energy of C(4)-F(10)decreases fastest,and it is most likely that the breakdown under external electric field will destroy the symmetry of c-C4F8.The data shows that the adiabatic electron affinity increases monotonously,the ability to absorb free electrons becomes well.In the molecular infrared spectrum,the number of absorption peaks increases,and the four main absorption peaks are red-shifted.