Valerie Vaissier

2D molecular self assembly - Quantifying electrostatic interactions in
monolayers of charged molecules with CDFT 

ABSTRACT
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Molecular materials in electronic devices, such as Dye Sensitized Solar
Cells (DSSC) or photocatalytic systems for water-splitting, are 2D self
assembled monolayers. This implies that intermolecular forces control the
architecture, hence the properties, of these systems. Since this phenomenon
is difficult to characterize experimentally, there is a demand for
simulations to assist the design of electronic devices. However, it is
challenging for two reasons. First, it requires precise calculations to
capture the effect of the weak intermolecular forces among the covalent
interactions which bind the atoms together. Second, relatively big systems
are needed (at least a pair of molecules) within which a charge (excess
electron) is locally distributed.  
In this talk, I am going to present charge constrained DFT (CDFT)
calculations on electron transfer systems. CDFT overcome conventional DFT by
providing a means to calculate the electronic structure of a pair of charged
molecules. The focus is going to be on quantifying electrostatic
interactions as a function of the intermolecular separation. This allows me
to calculate more accurately the reorganization energy of charge transfer
and link the kinetics of charge transport to the structure of a given
molecular monolayer.