  We have recently developed a method based on relativistic time-dependent
density functional theory (TD-DFT) that allows the calculation of electronic
spectra in solution (Creutzberg, Hedeg{\aa}rd, J. Chem. Theory Comput.18, 2022,
3671). This method treats the solvent explicitly with a classical, polarizable
embedding (PE) description. Furthermore, it employs the complex polarization
propagator (CPP) formalism which allows calculations on complexes with a dense
population of electronic states (such complexes are known to be problematic for
conventional TD-DFT). Here, we employ this method to investigate both the
dynamic and electronic effects of the solvent for the excited electronic states
of trans-trans-trans-[Pt(N3)2(OH)2(NH3)2] in aqueous solution. This complex
decomposes into species harmful to cancer cells under light irradiation. Thus,
understanding its photo-physical properties may lead to a more efficient method
to battle cancer. We quantify the effect of the underlying structure and
dynamics by classical molecular mechanics simulations, refined with a
subsequent DFT or semi-empirical optimization on a cluster. Moreover, we
quantify the effect of employing different methods to set up the solvated
system, e.g., how sensitive the results are to the method used for the
refinement, and how large a solvent shell that is required. The electronic
solvent effect is always included through a PE potential.
