anchor.diff:         solvent_pos(3,o) = solvent_pos(3,o)+colloids% pos(3,1)
          if (solvent% species(o)==2) then
             check = floor(solvent_pos(3,o)/dz)
  +          !$omp atomic
             conc_z(check) = conc_z(check) + 1
          end if 
       end do
  +
       colloid_pos(:,1) = 0
       colloid_pos(3,1) = colloids% pos(3,1)
       colloid_pos(:,2) = 0
  
positive.code:   double precision :: x(3)
    
    call random_number(rndnumbers)
    
    do  r = 1,solvent% Nmax
       if (solvent% species(r) == 1) then
         x = rel_pos(colloids% pos(:,1),solvent% pos(:,r),solvent_cells% edges) 
  
negative.code:     integer :: m
      double precision :: x(3)
  
      !$omp parallel do private(x, dist_to_C_sq, dist_to_N_sq)
      do m = 1, solvent% Nmax
         if (solvent% flag(m) == 1) then
            x = rel_pos(colloids% pos(:,1), solvent% pos(:,m), solvent_cells% edges)
  