Anna Painelli (Parma, Italy) gave a really nice talk,
How molecular functional materials respond to the environment: from solvation to cooperativity.
She illustrated how simple model Hamiltonians can capture essential photophysical properties of complex molecular systems. The first system was a donor-acceptor (D-A) molecule in a solvent.
The simple model describes two electronic states (D-A and D+-A-), one vibrational mode, and the solvent which is described by one classical co-ordinate and a key parameter (the polarisability).
This nice paper from J. Phys. Chem A. in 2002 shows how this model gives a good quantitative description of the absorption and emission spectra for several different dyes in three different polar solvents.
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This 2006 JACS paper extends the model to describing "quadrupolar" molecule, which has the structure DAD . The model involves 3 electronic states, 2 vibrations, plus the solvent polarisation.
I am keen to apply this model for solvent effects to methine dyes, such as the Green Flourescent Protein chromophore, which Seth Olsen and I have argued is nicely described by a three state model.
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