anchor.diff:    double precision :: conc_z(400)
     double precision :: colloid_pos(3,2)
     type(h5md_file_t) :: hfile
  +  type(h5md_element_t) :: dummy_element
     type(thermo_t) :: thermo_data
  +  type(particle_system_io_t) :: dimer_io
  +  type(particle_system_io_t) :: solvent_io
  +  integer(HID_T) :: box_group
   
     type(PTo) :: config
     integer(c_int64_t) :: seed
  
positive.code:   call thermo_data%append(hfile, temperature, e1+e2+e_wall, kin_e, e1+e2+e_wall+kin_e, add=.false., force=.true.)
  
    write(*,*) 'n extra sorting', n_extra_sorting
    
    call h5close_f(error)
  
    write(*,'(a16,f8.3)') solvent%time_stream%name, solvent%time_stream%total
  
negative.code: 
    call PTkill(config)
  
    dimer_io%force_info%store = .false.
    dimer_io%id_info%store = .false.
    dimer_io%position_info%store = .true.
    dimer_io%position_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    dimer_io%position_info%step = N_MD_steps
    dimer_io%position_info%time = N_MD_steps*dt
    dimer_io%image_info%store = .true.
    dimer_io%image_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    dimer_io%image_info%step = N_MD_steps
    dimer_io%image_info%time = N_MD_steps*dt
    dimer_io%velocity_info%store = .true.
    dimer_io%velocity_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    dimer_io%velocity_info%step = N_MD_steps
    dimer_io%velocity_info%time = N_MD_steps*dt
    dimer_io%species_info%store = .true.
    dimer_io%species_info%mode = H5MD_FIXED
    call dimer_io%init(hfile, 'dimer', colloids)
  
    solvent_io%force_info%store = .false.
    solvent_io%id_info%store = .false.
    solvent_io%position_info%store = .true.
    solvent_io%position_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    solvent_io%position_info%step = N_loop*N_MD_steps
    solvent_io%position_info%time = N_loop*N_MD_steps*dt
    solvent_io%image_info%store = .true.
    solvent_io%image_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    solvent_io%image_info%step = N_loop*N_MD_steps
    solvent_io%image_info%time = N_loop*N_MD_steps*dt
    solvent_io%velocity_info%store = .true.
    solvent_io%velocity_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    solvent_io%velocity_info%step = N_loop*N_MD_steps
    solvent_io%velocity_info%time = N_loop*N_MD_steps*dt
    solvent_io%species_info%store = .true.
    solvent_io%species_info%mode = ior(H5MD_LINEAR,H5MD_STORE_TIME)
    solvent_io%species_info%step = N_loop*N_MD_steps
    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(19,file ='dimerdata_vx_flow_wall.txt')  
  
    colloids% species(1) = 1
  