外电场作用下SiS分子结构及其特性研究

采用密度泛函B3P86/6-311++g(d,p)方法研究了在不同外电场(-0.03～0.03a.u.)作用下SiS基态分子的几何结构、能级分布、能隙、红外光谱及势能曲线等的变化规律。结果表明:随外电场(Si→S方向)的增大,SiS分子键长逐渐增大,分子振动频率和红外光谱强度逐渐减小,总能量逐渐升高,当F=-0.01a.u.时,能量达到最大,随后继续增大电场强度系统总能量开始降低;EH和EL及能隙随电场的增加逐渐增大,当F=0.02a.u.时,EH和EL及能隙均达到最大值,随着电场的继续增大,能级EH和EL及能隙逐渐减小;基态分子势能曲线对外电场方向有明显依赖关系。

Study on the molecular structure and properties of SiS in the external electric field

The density functional theory(DFT) B3P86/6-311++g(d,p) method has been used to study the equilibrium geometry,energy levels,HOMO-LUMO gaps,infrared spectrum and the potential energy curve of the ground states of SiS in different external electric fields ranging from -0.03 to 0.03a.u.The results show that the molecular bond length gradually increases,but the molecular frequencies and IR intensity gradually decrease with increase of the external field along the molecular axis Si→S. As the electric field increased to -0.01a.u.,the total molecule energy reaches the maximum. Further increase of the electric field results in a decrease of the total energy. As the electric field increased to 0.02a.u.,the HOMO energy level,LUMO energy level and HOMO-LUMO gaps reaches the maximum. Then the HOMO energy level,LUMO energy level and HOMO-LUMO gaps gradually decrease with increase of the external field. The potential energy curve of the ground states of SiS molecule are strongly dependent on the direction of external field.