Two-dimensional free energy surfaces for primary electron transfer in a photosynthetic reaction center

Two-dimensional free energy surfaces for primary electron transfer in a bacterial photosynthetic reaction center are constructed from the MD simulation results by Warshel et al. [J. Photochem. Photobiol. A: Chem 82 (1994) 123] on the same system by choosing the reaction coordinates appropriately. The activation energies for the direct and sequential electron transfer are calculated using these surfaces. One needs these two-dimensional free energy surfaces to analyze the dynamical solvent effect on the competition between the direct and sequential electron transfer properly, although this effect has so far been analyzed by using one-dimensional free energy curves.