具有相干与压缩关联的非绝热的电子声子耦合系统的状态表示和基态特征(英文)

THE STATE ANSATZ AND THE GROUND STATE FOR COUPLING NONADIABATICALLY ELECTRONPHONON SYSTEMS WITH CORRELATED DISPLACEMENT AND SQUEEZING

求出了在电子声子耦合系统中由于电子密度的涨落所导致的非绝热声子对系统的基态，极化子的特征和声子测不准关系的量子修正，在这计算中我们使用了一个表征相干压缩声子和电子有相互关联的新的变分表示式．由此求出的系统基态比无关联时的基态更加稳定，极化子能带变窄的效应受到抑制，由于同电子的非绝热耦合而使声子的测不准关系增量．研究表明具有相干压缩关联的新状态表示对于大压缩特性和强耦合情况特别适合．

We have found effects of the nonadiabatic phonon behaviour on the ground state of the electron phonon system, the quantum modifications of the polaron characteristics and the modification of the phonon coordinate uncertainty due to fluctuations of the electron density.We here used a variational ansatz for squeezed coherent phonons with correlated displacement and squeezing including correlations with electrons. The ground state of the system is found to be lower than that one for phonons with uncorrelated displacement and squeezing. The polaron narrowing of the electron band was found to be reduced.The nonadiabatic coupling with electrons enhances the quantum uncertainty for the phonon coordinate when compared with the adiabatic case. The correlation of the displacement and squeezing was found relevant for sufficiently large sqeezing and strong coupling case.