  Light harvesting as the first step in photosynthesis is of prime importance
for life on earth. For a theoretical description of photochemical processes
during light harvesting, spectral densities are key quantities. They serve as
input functions for modeling the excitation energy transfer dynamics and
spectroscopic properties. Herein, a recently developed procedure is applied to
determine the spectral densities of the pigments in the minor antenna complex
CP29 of photosystem II which has recently gained attention because of its
active role in non-photochemical quenching processes in higher plants. To this
end, the density functional based tight binding (DFTB) method has been employed
to enable simulation of the ground state dynamics in a
quantum-mechanics/molecular mechanics (QM/MM) scheme for each chlorophyll
pigment. Subsequently, the time-dependent extension of the long-range corrected
DFTB approach has been used to obtain the excitation energy fluctuations along
the ground-state trajectories also in a QM/MM setting. From these results the
spectral densities have been determined and compared for different force fields
and to spectral densities from other light-harvesting complexes. In addition,
the excitation energy transfer in the CP29 complex has been studied using
ensemble-average wave packet dynamics.
