CHANGES IN THE PHYSICAL PROPERTIES OF NONADIABATICALLY COUPLED ELECTRON–PHONON SYSTEMS ARISING FROM SQUEEZING–ANTISQUEEZING EFFECT

Abstract

Changes in the physical properties such as the ground state properties, charge density wave ordering, binding energy and energy bandwidth of polaron and quantum fluctuation, and minimum uncertainty relation of phonons and nonadiabatically coupled electron–phonon systems with spin-1/2 have been investigated by our new state ansatz which can account for correlation among the phononic displacement, squeezing and polaron effects using variational method in one-dimensional Holstein model. The investigation here shows that the squeezing–antisqueezing effect (correlated) results in a decrease of the ground state energy, an increase of the binding energy of polarons, the reduction of the uncertainty and quantum fluctuation of the phonons, a decrease of polaron narrowing of electron bandwidth, an increase of tunneling effect of the polarons and an increase of CDW ordering and phonon staggered ordering when compared with the uncorrelated case. Therefore, this shows that the ground state determined by the new state ansatz is the most stable. The new ansatz which include the squeezing–antisqueezing (correlated) effect is very relevant for the coupled electron–phonon systems, especially in strongly coupled and highly squeezed cases.