anchor.diff:    call dummy_element%create_fixed(box_group, 'edges', solvent_cells%edges)
     call h5gclose_f(box_group, error)
   
  +  call h5gcreate_f(hfile%id, 'fields', fields_group, error)
  +  call radial_hist%init(sigma/2, 4*sigma, 100)
  +  call radial_hist_el%create_time(fields_group, 'radial_histogram', radial_hist%data, &
  +       H5MD_LINEAR, step=N_MD_steps, time=N_MD_steps*dt)
  +  call h5md_write_attribute(radial_hist_el%id, 'xmin', radial_hist%xmin)
  +  call h5md_write_attribute(radial_hist_el%id, 'dx', radial_hist%dx)
  +  call h5gclose_f(fields_group, error)
  +
     i = 1
     place_colloids: do while (i<=N_colloids)
        colloids%pos(1,i) = threefry_double(state(1))*L(1)
  
positive.code:   integer(HID_T) :: box_group
    type(h5md_element_t) :: dummy_element
  
    double precision :: skin
    double precision :: rsq
    logical :: tooclose
  
negative.code: 
       call thermo_data%append(hfile, temperature, e1+e2, kin_e, e1+e2+kin_e, v_com)
  
       radial_hist%data = 0
       call compute_radial_histogram(radial_hist, colloids%pos(:,1), &
            solvent_cells%edges, solvent)
       call radial_hist_el%append(radial_hist%data)
  
    end do
  
    call thermo_data%append(hfile, temperature, e1+e2, kin_e, e1+e2+kin_e, &
  