电子-晶格耦合非线性项对极化子性质的影响

Effects of nonlinear electron-lattice interaction on polarons

基于一维紧束缚SSH模型,讨论了电子晶格耦合二阶项对极化子静态和动力学性质的影响:随着二阶项系数β的增加,二聚化常数越来越大,能隙越来越宽,极化子的局域性不断增强,但带宽几乎没有变化.动力学方面由于二阶项的引入增强了电声相互作用,随着β值的增大,极化子的运动速度减小,并且极化子的解离电场不断增大.

Based on the Su-Schrieffer-Heeger （ SSH ） model extended to include the square term of the electron-lattice interaction,the dynamic characteristics of polarons are investigated. With increasing of the coefficient of the square term （β）,the energy gap between the valance band and the conduction band increases. but the total width of the energy band does not change. At the same time,it is found that the dimerization amplitude and the localization of polarons are strengthened by the nonlinear electron-lattice interaction. Furthermore,the results show that the polaron velocity is suppressed by the nonlinear electron-lattice interaction,and the critical electric field strength to dissociate the polaron increases with β increasing.