  We investigate the time an electronic excitation travels in a supermolecular
setup using a measurement process in an open quantum-system framework. The
approach is based on the stochastic Schr\"odinger equation and uses a
Hamiltonian from time-dependent density functional theory (TDDFT). It treats
electronic-structure properties and intermolecular coupling on the level of
TDDFT, while it opens a route to the description of dissipation and relaxation
via a bath operator that couples to the dipole moment of the density. Within
our study, we find that in supermolecular setups small deviations of the
electronic structure from the perfectly resonant case have only minor influence
on the pathways of excitation-energy transfer, thus lead to similar transfer
times. Yet, sizable defects cause notable slowdown of the energy spread.
