Understanding energy transfer after excitation has enormous relevance to biological processes, such as photosynthesis, as well as being of purely fundamental interest. We present a method for studying the movement of electrons and energy within and between electronically excited molecules. The dynamically changing state is a many-electron wavepacket. We have developed the tools necessary for following the separate motions of the particles and holes. In addition to demonstrating our propagation and analysis machinery, the results show a dramatic difference in excitation-energy transfer rates in a neon chain as a consequence of initial polarization. Furthermore, already in a system with three constituents, an important aspect of multiple coupled systems appears, in that one absorbing system essentially shields another, changing the effective site-wise coupling parameters. Finally we show interesting examples where an initially local excitation results in a charge separated state, because the excited electron and the vacant hole have different mobilities through different regions of the molecule.

Tracing Molecular Electronic Excitation Dynamics in Real Time and Space