Classical dynamics of a coupled double-well oscillator in condensed media. III. The constraint of detailed balance and its effects on chemical reaction process

The reacting system is assumed to interact both with an ideal thermal source at the temperature T1 and a (fast) nonreactive oscillator coupled to an ideal thermal source at temperature T2. Special attention is devoted to the case T1=T2 which is characterized by equilibrium distributions of canonical kind. We use the same adiabatic elimination procedure (AEP) as applied in our earlier works [J. Chem. Phys. 79, 3320 (1983); 80, 1826 (1984)] with a projection operator that allows the canonical property to be recovered in the reduced equation of motion. It is shown that in the underdamped regime the chemical reaction rate increases with increasing strength of the coupling between reactive and nonreactive mode. In the high-friction regime the chemical reaction rate decreases with increasing reactive–nonreactive mode coupling. Arguments are also provided for a more complete picture covering the whole friction region. It is also shown that the projection operator used in the two preceding papers implies that T2≫T1.