anchor.diff:       if (block_length**n_blocks >= N_loop*N_MD_steps/block_length) exit
     end do
     call vacf%init(block_length, n_blocks, dim=3)
  +  call parallel_vacf%init(block_length, n_blocks, dim=3)
  +  call transverse_vacf%init(block_length, n_blocks, dim=3)
   
     if (dimer) then
        colloids% species(1) = 1
  
positive.code:            ! correlators
             call msd%add(i_block, correlate_block_distsq, xvec=com_pos)
             call omega_acf%add(i_block, correlate_block_dot, x=omega(3))
             unit_r = unit_r / norm2(unit_r)
             call oacf%add(i_block, correlate_block_dot, xvec=unit_r)
             i_block = i_block + 1
             ! colloid trajectory
  
negative.code: 
    integer, parameter :: block_length = 8
    integer :: n_blocks
    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
  
  