anchor.diff:  
     integer, parameter :: block_length = 8
     integer :: n_blocks
  -  type(correlator_t) :: msd, omega_acf, oacf, vacf
  -  integer(HID_T) :: correlator_group, group
  +  type(correlator_t) :: msd, omega_acf, oacf, vacf, parallel_vacf, transverse_vacf
  +  integer(HID_T) :: correlator_group
   
     double precision :: unit_r(3), omega(3), rel_v(3), norm_xy
   
  
positive.code:      if (block_length**n_blocks >= N_loop*N_MD_steps/block_length) exit
    end do
    call vacf%init(block_length, n_blocks, dim=3)
  
    if (dimer) then
       colloids% species(1) = 1
  
negative.code:   double precision,allocatable :: mass(:)
  
    double precision :: v_com(3), wall_v(3,2), wall_t(2)
    double precision :: parallel_v(3), transverse_v(3)
    double precision :: local_mass, total_mass
  
    double precision :: e1, e2, e_wall
  