  We report microscopic calculations of free energies and entropies for
intramolecular electron transfer reactions. The calculation algorithm combines
the atomistic geometry and charge distribution of a molecular solute obtained
from quantum calculations with the microscopic polarization response of a polar
solvent expressed in terms of its polarization structure factors. The procedure
is tested on a donor-acceptor complex in which ruthenium donor and cobalt
acceptor sites are linked by a four-proline polypeptide. The reorganization
energies and reaction energy gaps are calculated as a function of temperature
by using structure factors obtained from our analytical procedure and from
computer simulations. Good agreement between two procedures and with direct
computer simulations of the reorganization energy is achieved. The microscopic
algorithm is compared to the dielectric continuum calculations. We found that
the strong dependence of the reorganization energy on the solvent refractive
index predicted by continuum models is not supported by the microscopic theory.
Also, the reorganization and overall solvation entropies are substantially
larger in the microscopic theory compared to continuum models.
