title: Enhancement of vibronic and ground-state vibrational coherences in 2D spectra of photosynthetic complexes.
abstract: A vibronic-exciton model is applied to investigate the recently proposed mechanism of enhancement of coherent oscillations due to mixing of electronic and nuclear degrees of freedom. We study a dimer system to elucidate the role of resonance coupling, site energies, vibrational frequency and energy disorder in the enhancement of vibronic-exciton and ground-state vibrational coherences, and to identify regimes where this enhancement is significant. For a heterodimer representing two coupled bachteriochloropylls of the FMO complex, long-lived vibronic coherences are found to be generated only when the frequency of the mode is in the vicinity of the electronic energy difference. Although the vibronic-exciton coherences exhibit a larger initial amplitude compared to the ground-state vibrational coherences, we conclude that, due to the dephasing of the former, both type of coherences have a similar magnitude at longer population time.
authors.affiliation: Faculty of Mathematics and Physics, Charles University in Prague, Prague 2, Czech Republic.
authors.forename: Aurélia
authors.initials: A
authors.lastname: Chenu
authors.forename: Niklas
authors.initials: N
authors.lastname: Christensson
authors.forename: Harald F
authors.initials: HF
authors.lastname: Kauffmann
authors.forename: Tomáš
authors.initials: T
authors.lastname: Mančal