A method is proposed to evaluate the Grote-Hynes transmission coefficient based on the reference interaction site model self-consistent field (RISM-SCF) electronic structure calculations of reacting solute molecules combined with molecular dynamics simulation calculations of bulk solvent. The time dependent solvent friction acting on the reaction coordinate mode is derived using the linear response approximation. An application of the present method is made to the S(N)2 reaction CH3Cl + Cl- in aqueous solution. The transmission coefficient is calculated to be 0.71, which is consistent with the previous simulation studies.