  Charge transfer between photoexcited quantum dots and molecular acceptors is
one of the key limiting processes in most applications of colloidal
nanostructures, most prominently in photovoltaics. An atomistic detailed
description of this process would open new ways to optimize existing and create
new structures with targeted properties. We achieve a one-to-one comparison
between ab-initio non-adiabatic molecular dynamics calculations and transient
absorption spectroscopy experiments, which allows us to draw a comprehensive
atomistic picture of the charge transfer process, following the time evolution
of the charge carrier across the electronic landscape and identifying the
thereby induced vibrations. For two quantum dot sizes we find two qualitatively
different processes. For the larger structure we find a relatively slow (\tau =
516 fs) transfer process that we explain by the existence of a large energy
detuning and weak vibronic coupling. For the smaller structure the process is
ultrafast (\tau = 20 fs) due to an efficient, phonon-assisted Auger process
triggered by a strong electron-hole coupling.
