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How solvent controls electronic energy transfer and light harvesting: Toward a quantum-mechanical description of reaction field and screening effects

Posted September 5th, 2013 by ccurutchet
TitleHow solvent controls electronic energy transfer and light harvesting: Toward a quantum-mechanical description of reaction field and screening effects
Publication TypeJournal Article
Year of Publication2007
AuthorsCurutchet, C, Scholes GD, Mennucci B, Cammi R
JournalJournal of Physical Chemistry B
Volume111
Issue46
Pagination13253 - 13265
Date Published2007
ISBN Number1520-6106
Keywordscondensed matter, conjugated polymers, density cube method, dielectric-properties, molecular-dynamics simulations, polarizable continuum model, purple bacteria, rhodopseudomonas-acidophila, scale interpretation, solvated bichromophoric systems
AbstractThis paper presents a quantum-mechanical study of electronic energy transfer (EET) coupling on over 100 pairs of chromophores taken from photosynthetic light-harvesting antenna proteins. Solvation effects due to the protein, intrinsic waters, and surrounding medium are analyzed in terms of screening and reaction field contributions using a model developed recently that combines a linear response approach with the polarizable continuum model (PCM). We find that the screening of EET interactions is quite insensitive to the quantum-mechanical treatment adopted. In contrast, it is greatly dependent on the geometrical details (distance, shape, and orientation) of the chromophore pair considered. We demonstrate that implicit (reaction field) as well as screening effects are dictated mainly by the optical dielectric properties of the host medium, while the effect of the static properties is substantially less important. The empirical distance-dependent screening function we proposed in a recent letter (Scholes, G. D.; Curutchet, C.; Mennucci, B.; Cammi, R.; Tomasi, J. J. Phys. Chem. B 2007, 111, 6978-6982) is analyzed and compared to other commonly used screening factors. In addition, we show that implicit medium effects on the coupling, resulting from changes in the transition densities upon solvation, are strongly dependent on the particular system considered, thus preventing the possibility of defining a general empirical expression for such an effect.