Self-consistent harmonic theory of solvation in glassy systems: Classical solvation

Various harmonic theories of classical solvation dynamics in glassy systems are discussed. The "optimized normal mode'' theory is found to provide a s ubstantial improvement over more standard normal mode approaches for the de scription of solvation dynamics in both glassy and supercooled media. A met hodology is developed to include all multiphonon terms in the expansion of the collective solvation coordinate, thus going beyond "linear'' solvation theories. The results suggest that the methods described here can provide a quantitative description of solvation over a wide temperature range in sys tems of low diffusiveness. Lastly, the extension of Zwanzig's model of self -diffusion in supercooled media to the treatment of solvation phenomena is discussed. (C) 2000 American Institute of Physics. [S0021-9606(00)50905-2].