Correlations and delocalization in excitonic model

Darius Abramavicius, Olga Rancova
Department of Theoretical Physics, Vilnius University, Sauletekio al. 9-III, 10222, Vilnius, Lithuania

Degrees of freedom (DOF) of molecular systems split into electronic DOF, which interact with the optical fields, and nuclear DOF, which modulate the induced polarization. The nuclear DOF can be characterized by the spectral density function. The spectral density is often obtained from low temperature measurements (using hole burning (HB), fluorescence line narrowing (FLN) etc.), where the spectral density function becomes clearly imprinted onto the spectral line shape [1]. Two dimensional electronic spectra (2DES) at low temperature reveals complex interaction patterns related to the specific electronic transitions and vibrational modes [2]. Simulations 2DES of photosynthetic complexes WSCP and bRC [3] demonstrate that intermolecular correlations of site energy fluctuations can be unambiguously determined from the spectra at low temperature (Fig.1). The correlations turn to be very important in reaction centers for molecular excitation and bi-exciton energies.

References

[1] R. Jankowiak, et al., Chem. Rev. 111, 4546 (2011).
[2] O. Rancova, R. Jankowiak, D. Abramavicius, J Chem. Phys. 142, 212428 (2015).
[3] O. Rancova, , R. Jankowiak, A. Kell, M. Jassas, D. Abramavicius, J. Phys. Chem. B. (submitted)