An improved variational approach to off-diagonal exciton-phonon coupling.
A state-of-the-art variational wave function incorporating Jastrow-type exciton-phonon correlations, the global-local Ansatz, is utilized to elucidate exciton-phonon correlations in a generalized form of the Holstein Hamiltonian with the simultaneous presence of diagonal and off-diagonal exciton-phonon coupling. Much lowered ground-state energies are found for the global-local Ansatz when compared with the previously studied Toyozawa Ansatz. A three-dimensional phase diagram spanned by the transfer integral and two forms of exciton-phonon coupling is given to illustrate polaronic self-trapping near the zone center.
Zhao
Yang
Y
School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore. yzhao@ntu.edu.sg
Li
Guangqi
G
Sun
Jin
J
Wang
Weihua
W