Variational Approach to One-Dimensional Electrons Non- Adiabatically Coupled to Phonons
PANG Xiao-feng
Department of Physics, Southwest Institute for Nationalities, Chengdu 610041,
International Centre for Material Physics, Chinese Academy of Sciences, Shenyang 110015,
and Institute of Atomic and Molecular Physics, Sichuan Union University, Chengdu 610065
Variational Approach to One-Dimensional Electrons Non- Adiabatically Coupled to Phonons
PANG Xiao-feng
Department of Physics, Southwest Institute for Nationalities, Chengdu 610041,
International Centre for Material Physics, Chinese Academy of Sciences, Shenyang 110015,
and Institute of Atomic and Molecular Physics, Sichuan Union University, Chengdu 610065
Abstract： The effects of the nonadiabatic phonon behaviours on the ground state of the system and the quantum modifications of the polaron characteristics and the modification form of the uncertainty relation between the phonon coordinate and momentum due to fluctuations of the electron density in the coupled electron-phonon systems have been studied by using a new variational ansatz for coherent phonons with correlated displacement and squeezing including internations with electrons. The correlated effect results in the following effect: (1) the energy of the ground state of the system is found to be lower than that for the phonons with uncorrelated displacement and squeezing; (2) the binding energy of the polaron was found to be increased; (3) the nonadiabatic coupling with electrons enhances the quantum uncertainty for the phonon coordinate and momentum when compared with the adiabatic and uncorrelated case.
1999, Vol. 16 
