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Energy transport through molecular systems has received considerable interest, in particular, due to its importance for molecular electronics and the functioning of biological systems. In experiment, energy is usually induced into the molecule by photoexcitation of a chromophore or by pumping a localized infrared vibration. This triggers an cascade of dynamical processes including (i) the femtosecond vibrational energy redistribution from localized high-frequency modes to delocalized low-frequency modes, (ii) transport of energy through the molecule, and (iii) the cooling the molecules due to heat transfer to the solvent. To study these processes in biomolecules such as peptides, proteins, and RNA, we combine quantum-classical techniques well-known from the description of gas phase reactions with biomolecular force fields typically used in all-atom molecular dynamics simulations. This leads to nonequilibrium molecular dynamics simulations, which mimic the laser excitation of the molecules by nonequilibrium phase-space initial condition for the solute and the solvent atoms. To understand the quantum effects involved, we furthermore perform classical and quantum-mechanical perturbation theory. The results are discussed in the light of recent time-resolved infrared experiments. |