anchor.diff:             call change_timer%tac()
           end if
   
  -     end do md
  +     end do md_loop
   
        
   
  
positive.code:         fixed = .false.
       end if
       if (.not. on_track) then
          if (modulo(i,50)==0) then
             call concentration_field_cylindrical
             write(18,*) conc_z, colloid_pos
           end if
  
negative.code:   integer :: error
    double precision :: number_of_angles
    double precision, allocatable :: conc_z(:,:)
    double precision :: conc_z_cyl(90)   
  
    double precision :: sigma_N, sigma_C, max_cut
    double precision :: epsilon(3,2), shift
  