Linear response and electron transfer in complex biomolecular systems and a reaction center protein

This paper is focused on the dielectric linear response in the context of electron-transfer reactions in complex biomolecules with and without explicit electronic polarization. Molecular dynamics simulation is used for a detailed investigation of two systems: a bacteriochlorophyll molecule in a homogeneous environment (liquid water) and a reaction center protein of bacterial photosynthesis in amphophilic solution. The limits of the linear approximation and the size of its deviation from the results, in principle exact, obtained from thermodynamic integration are pinpointed. Our findings will be of crucial importance in further investigations of electron transfer in complex biomolecules making use of linear response, still the easiest and least time- consuming approach.