Tracing Electronic Dynamics of Molecules in Real Time and Space: A Study of Excitation Transfer and Charge Separation

Understanding energy transfer and charge separation after excitation has enormous relevance to biological processes, such as photosynthesis, as well as being of purely fundamental interest and having potential applications in molecular electronics. We have developed a method for studying the movement of electrons and energy within and between electronically excited molecules, which produces descriptive animations of quasi-particle (particlehole) motion. The dynamically changing state is a manyelectron wavepacket, for which we numerically integrate the Schrödinger equation using the ADC(2) effective Hamiltonian for the particle-hole propagator. We apply this to examples of simple resonant energy transfer and transfer through non-resonant intermediaries. Excitation transfer rates depend strongly on alignment of transition dipole moments, and, already in a system with three constituents, an important aspect of multiple coupled systems appears, in that one absorbing system essentially shields another. In specific hole-doped and particle-doped π systems, we observe a difference in particle and hole mobilities which causes charges to separate periodicall