抛物量子点中强耦合双极化子的有效势

Effective Potential of Strong-Coupling Bipolaron in a Parabolic Quantum Dot

基于Lee-Low-Pines-Huybrechts变分方法研究了抛物量子点中强耦合双极化子的基态性质,并推导出了量子点中强耦合双极化子有效势Veff随电子-声子耦合强度α、两电子相对距离r和量子点半径R0的变化规律。结果表明,有效势Veff由库仑势Vcoul、量子点的限定势Vconf和诱生势Ve-LO三部分组成;其中诱生势Ve-LO总是小于零,其绝对值Ve-LO随电子-声子耦合强度α的增加而增大,随电子间相对距离r和量子点半径R0的减小而增大。双极化子有效势的绝对值Veff随电子-声子耦合强度α的增加而增大,随电子间相对距离r的减小而增大。耦合强度α和电子间相对距离r是影响有效势Veff的主要因素,而量子点半径R0和介电常数比η对有效势Veff的影响较小。

The ground state properties of the strong coupling bipolarons in a parabolic quantum dot are studied based on the Lee-Low-Pines-Huybrechts variational method. The law of the effective potential Veff of the strong coupling bipolarons changing with the strength of the electron-phonon coupling α, the relative distance between two electrons r, and the radiu of quantum dot R0 are derived. The results show that Veff consists of three parts： Coulomb potential Vcoul, confining potential Vconf and induced potential Ve-LO. Ve-LO is always less than zero, and the absolute value ｜Ve-LO｜ increases when the strength α, and increases when the relative distance r between the electrons and guantum dot′s radius R0 decreace. The absolute value ｜Veff｜ increases with the strength α increasing and increases with the relative distance r decreasing. α and r are the main factors to influence the effective value. However, the quantum dot′s radius R0 and the dielectric constant ratio η have little influence on the effective potential Veff.