Polaron formation and symmetry breaking

In a molecular semiconductor, a charged molecule experiences a lattice relaxation which reorganizes it into a cation or an anion-radical. This species is not, in general, a polaron. By using calculations of the geometry and the electronic structure both ab initio and at the semi-empirical levels, we have explored the conditions of polaron formation in a molecular model system: oligophenylene-vinylenes, PVs of increasing sizes. The symmetry breaking occurs at sizes larger than five monomers for the anion and six monomers for the cation. The driving force for this process is primarily the charge-lattice coupling through the stretching mode at 1600 cm<sup>-1</sup>


Published in:
Chemical Physics Letters, 374, 1-2, 7
Year:
2003
Publisher:
Elsevier
Keywords:
Note:
Copyright 2004, IEE
7825706
0009-2614
symmetry breaking
polaron formation
molecular semiconductor
charged molecule
lattice relaxation
electronic structure
ab initio calculations
semiempirical calculations
oligophenylene-vinylenes
charge-lattice coupling
stretching mode
conducting polymers
local density approximation
pseudopotentials
plane wave expansions
vibration spectra
neglect of diatomic differential overlap
AM1
Hartree-Fock framework
electron density distribution
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Laboratories:




 Record created 2007-04-03, last modified 2018-03-17


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