Role of disorder and fluctuation on charge migration dynamics in molecular aggregate with quantum mechanical network

Abstract

We examine the effect of structural disorder and dynamical lattice fluctuation on charge migration dynamics starting from a birth of local exciton in a quantum network of molecular aggregates by using model Hamiltonians having complicate interactions. Here all monomers are supposed to be the same for simplicity. A natural use of inherent sparsity of Hamiltonian matrix allows us an investigation of essential features in quantum network dynamics accompanied with a fluctuation of interaction. Variation of disorder parameter, kinetic energy and effective mass of monomers in electron dynamics calculation reveal how static disorder and dynamical fluctuation affects electron dynamics in a large size of molecular aggregates. Disorder in aggregate structure suppress charge separation while molecular motion can promote charge diffusion in cases of smaller mass. These findings are obtained by using a newly introduced formula for evaluating charge separation in molecular aggregates that is useful for other analysis involved with charge migration dynamics in molecular/atom aggregates. This work provides a way for obtaining a quantum mechanical time-dependent picture of diffusion and migration of exciton and charge density in general molecular aggregates, which offers a fundamental understanding of electronic functionality of nanocomposites.

13 pages, 3 figures, 1 table