anchor.diff:             fixed = .false.
           end if
        end if
  -     !if (.not. on_track) then
  -     !   if (modulo(i,20)==0) then
  -     !      call concentration_field_cylindrical
  -     !      write(18,*) conc_z_cyl, colloid_pos
  -     !    end if
  -     !end if 
        
     end do setup
   
  
positive.code:   solvent_io%species_info%time = N_loop*N_MD_steps*dt
    call solvent_io%init(hfile, 'solvent', solvent)
  
    open(17,file ='dimerdata_FullExp_1.txt')
    open(18, file ='concentration.txt')
    open(19,file ='dimerdata_vx_flow_wall.txt') 
   
    if (dimer) then
       colloids% species(1) = 1
       colloids% species(2) = 2
  
negative.code:         total_energy = e1+e2+e_wall+colloids% mass(1)*sum(colloids% vel(:,1)**2) + sum(solvent% vel**2)/2
       end if
  
       call random_number(solvent_cells% origin)
       solvent_cells% origin = solvent_cells% origin - 1
  
  