title: An improved variational approach to off-diagonal exciton-phonon coupling.
abstract: 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.
authors.affiliation: School of Materials Science and Engineering, Nanyang Technological University, Singapore 639798, Singapore. yzhao@ntu.edu.sg
authors.forename: Yang
authors.initials: Y
authors.lastname: Zhao
authors.forename: Guangqi
authors.initials: G
authors.lastname: Li
authors.forename: Jin
authors.initials: J
authors.lastname: Sun
authors.forename: Weihua
authors.initials: W
authors.lastname: Wang