max value = Pmax = fraction between 0.0 and 1.0
  diff value = M = multiplier on sum of diffusive distances 

Examples:

probability max 0.5
probability diff 1.5 

Description:

Set parameters that determine how binary reactions are computed for spatial simulations. A binary reaction occurs in a timestep with a probability P when a pair of reactant particles are within a cutoff distance R.

The max style uses the specifed Pmax to set one distance R for all reactions so that the fastest reaction (maximum rate constant) will occur with probability Pmax and give the desired k for a well-mixed system with diffusion-limited reactions. Since other reactions happen less frequently (smaller rate constants) their P values are set smaller than the specified Pmax.

The diff style sets a distance R for each reaction based on the diffusion coefficients of its 2 reactants. The sum of the root-mean squared value for each reactant is multipled by the specified M factor to compute R. The P for each reaction is then set so that each reaction happens at the desired frequency for a well-mixed system with diffusion-limitd reactions.

Note that values of P and R for individual reactions can be overridden via the react_modify command.

Restrictions:

This command can only be used for spatial simulations.

Related commands: none

Default:

max 0.5