Multiple external field effects on diffusion-limited reversible reactions for a geminate pair with no interparticle interactions

Kinetics of a geminate particle pair with no interparticle interactions controlled by diffusion-limited reversible reactions is investigated in the presence of various possible external fields such as electric or gravitational fields based on continuum theory. Diffusion equations subject to multiple external fields are analytically solved with Green functions and the physical quantities such as the binding and survival probabilities are derived. Particularly, the local binding probabilities at the specific location on the reaction surface depending on the initial distance and orientation and the field directions are calculated. The variations of the binding probabilities due to the change of the field directions are predicted at long times and it shows that the binding probabilities tend to shift along the sum of individual field directions.