anchor.diff:  
     write(*,*) 'n extra sorting', n_extra_sorting
   
  +  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)
  +
     call dimer_io%close()
  +  call solvent_io%close()
     call hfile%close()
     call h5close_f(error)
   
  
positive.code:   type(thermo_t) :: thermo_data
    double precision :: temperature, kin_e
    type(particle_system_io_t) :: dimer_io
  
    call PTparse(config,get_input_filename(),11)
  
  
negative.code:   colloids% pos(1,2) = colloids% pos(1,2) + d
  
    call h5gcreate_f(dimer_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)
  
    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)
  