Theory and simulation of organic solar cell model compounds: how packing and morphology determine the electronic conductivity.

We approach the electronic conductivity of simple models of organic solar cells containing linear and branched αα'-oligothiophenes and buckminsterfullerene. Close-packed model geometries are generated using a Monte Carlo method, this procedure is verified making use of an analogue model. The electronic structure is described by an extended Su-Schrieffer-Heeger Hamiltonian, the resulting potential energy surfaces relevant to charge transfer can be analyzed using Marcus' theory, leading to local and--via Kirchhoff's rule--global conductivities for uniform oligothiophene and fullerene systems and their mixtures.

Theory and simulation of organic solar cell model compounds: from atoms to excitons.

We approach the electronic properties of a simple model of organic solar cells, a binary mixture of αα'-oligothiophenes and buckminsterfullerene, from a theoretical and numerical perspective. Close-packed model geometries are generated using a Monte Carlo method, the electronic structure is described by a reparametrized semiempirical Pariser-Parr-Pople Hamiltonian. All electronic properties, such as optical absorption spectra, tightly-bound charge transfer states and exciton bands, arise from the same atomistic Hamiltonian using a configuration interaction method involving single excitations.

Semiempirical configuration interaction calculations in biochemical environments: parametrization and application to γD-crystallin, an eye-lens protein.

We approach the problem of optical excitations in molecular aggregates in complex biochemical environments from a computational, all-atom perspective. The system is divided into a π orbital part described by a Pariser-Parr-Pople model with configuration interaction using singly excited Slater determinants (PPP-CIS). It is coupled to the protein and water charges of a classical force field.