anchor.diff:    call dummy_element%create_fixed(box_group, 'edges', solvent_cells%edges)
     call h5gclose_f(box_group, error)
   
  -  call h5gcreate_f(solvent_io%group, 'box', box_group, error)
  -  call h5md_write_attribute(box_group, 'dimension', 3)
  -  call dummy_element%create_fixed(box_group, 'edges', solvent_cells%edges)
  -  call h5gclose_f(box_group, error)
  +  if (do_solvent_io) then
  +     call h5gcreate_f(solvent_io%group, 'box', box_group, error)
  +     call h5md_write_attribute(box_group, 'dimension', 3)
  +     call dummy_element%create_fixed(box_group, 'edges', solvent_cells%edges)
  +     call h5gclose_f(box_group, error)
  +  end if
   
     call h5gcreate_f(hfile%id, 'fields', fields_group, error)
     call radial_hist%init(0.d0, 5*sigma, 100, 2)
  
positive.code:   ! write solvent coordinates for last step
  
    call thermo_data%append(hfile, temperature, e1+e2+e3, kin_e, e1+e2+e3+kin_e, v_com, add=.false., force=.true.)
    call solvent_io%position%append(solvent%pos)
    call solvent_io%velocity%append(solvent%vel)
    call solvent_io%image%append(solvent%image)
    call solvent_io%species%append(solvent%species)
  
    ! store polar fields
  
  
negative.code: !! \param N_MD                  number MD steps occuring in tau
  !! \param N_loop                number of MPCD timesteps
  !! \param colloid_sampling      interval (in MD steps) of sampling the colloid position and velocity
  !! \param do_solvent_io         if true (T), a snapshot of the solvent in the final step is dump to the datafile
  !! \param equilibration_loops   number of MPCD steps for equilibration
  !! \param epsilon_C             interaction parameter of C sphere with both solvent species (2 elements)
  !! \param epsilon_N             interaction parameter of N sphere with both solvent species (2 elements)
  