anchor.diff:    logical :: bulk_rmpcd
   
     logical :: enzyme_bound
  -  integer :: bound_molecule_idx
  +  integer :: bound_molecule_id
     double precision :: enzyme_capture_radius
     double precision :: proba_p, proba_s
  +  double precision :: rate_release_p, rate_release_s, total_rate, next_reaction_time
     double precision :: substrate_fraction
   
     integer, dimension(N_species) :: n_solvent
  
positive.code:                (dist < solvent_colloid_lj%cut(to_species, colloids%species(i)))
         end do
      end do
      solvent%pos(:,bound_molecule_idx) = x_new
  
      ! Use c.o.m. velocity so that no kinetic energy exchange must take place
      solvent%vel(:,bound_molecule_idx) = colloids%vel(:,2)
  
      enzyme_bound = .false.
  
  
negative.code: 
      ! transfer mass
      colloids%mass(1) = colloids%mass(1) - 1
  
      ! Place the molecule outside of the interaction range of all colloids
      too_close = .true.
  