紧束缚模型下有限尺寸的简立方晶格体系等离激元的偶极模式

Dipole Mode of Plasmon in Finite-Size Simple Cubic Lattice System of Tight-Binding Model

摘要: 基于紧束缚模型，发展了线性响应理论构造了有限尺寸的简立方晶格体系的偶极响应函数。通过偶极响应函数随外加电势场频率的变化关系，指出简立方晶格体系等离激元的偶极模式被外场激发时，偶极响应函数的实部会出现反转，偶极响应函数的虚部会出现极大值。这些结果意味着等离激元的偶极模式被激发时，体系对外加电势场的能量吸收有极大值，能量吸收的同时伴随偶极矩的剧烈振荡。进一步，我们给出在偶极等离激元处体系的电荷会在各个不同方向显示出偶极矩特征。

Abstract: Based on the tight-binding model, we developed the linear response theory to construct the dipole response function of finite-size simple cubic lattice systems. Through the change of dipole response function with the frequency of external electric potential field, we pointed out that when the dipole mode of the plasmon in a simple cubic lattice is excited by an external field, the real part of the dipole response function will be reversed and the imaginary part of the dipole response function will be maximized. These results imply that the energy absorbed by the system from the external potential field is extremely high at dipole plasmon, and the energy absorption is accomplished by the violently dipole moment oscillations. Furthermore, we show that the charge of the system will show dipole moment characteristics in different directions at dipole plasmon.