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利用数值计算研究了近邻原子质量和作用力常数均不同的一维链中的非线性表面局域模,该模型模拟闪锌矿结构晶体中〈111〉方向一列表面原子的非线性振动.在考虑近邻原子间相互作用势函数中的四次方非线性项后,在相应线性系统频带的禁带中和光学支上面发现了非线性表面局域模(S1模和S2模).在考虑近邻原子间相互作用势函数中的三次方和四次方非线性项时,非线性表面局域模中出现静态“直流”分量,表面局域模振动频率降低.结果还表明在相应线性系统频带的光学支上面和禁带中是否存在非线性表面局域模与三次方、四次方非线性项和最大的可能达到的位移有关.
The nonlinear surface local modes in a one-dimensional chain with different atomic mass and force constants are studied numerically. The model simulates the nonlinear vibration of a surface atom in the <111> direction in the sphalerite structure. After considering the fourth-order nonlinear term in the potential function of the inter-atom interaction, nonlinear surface local modes (S1 mode and S2 mode) are found in the forbidden band and the optical branch of the corresponding linear system band. At the same time, the static “DC ” component appears in the non-linear surface local mode, and the local mode vibration frequency decreases.The results also show that in the corresponding linear system Whether there is a non-linear surface local mode in the upper and the band gap of the optical band is related to the cubic, quaternary nonlinear terms and the maximum possible displacement.