Collective medium coordinates and their application in the theory of chemical reactions

摘要

A collective medium coordinate (CMC) represents a highly correlated motion of a large ensemble of medium particles, single variable, undergoes a significant change during a chemical process proceeding in this medium. CMCs naturally arit when charge transfer reactions in polar solvents are considered. In this context, the most important problems (1) quantum lnc CMC theory are: (I) quantum chemical compulations of free energy surfaces explicitly (renting a CMC as an esst-nti'1' coordinate, including location of minimum (reactants and products) and saddle (transition states) points on* these surfaces; f 3 ) derivation of stochastic dynamical equations lor CMCs and evaluation of their parameters, such as masses, friction coorfl deduction of the rate expression lor stochastic dynamical systems including CMCs. These problems are dissused JNing as examples electron and proton transfer mid SN2 reactions. Qualitative criterion formulated for when an cxpl is it consideration of a CMC is absolutely necessary and when it can be discarded.