anchor.diff:          type(excit)      :: connection_ki, connection_jk
           real(p)          :: psuccess, pspawn, pgen, hmatel
           type(det_info)   :: cdet_excit
  +
  +        integer(i0)      :: f_excit_2(basis_length)
  +
   
          ! specific to imperial code:
           !      -function that creates an excited determinant (create_excited_det)
  
positive.code:             ! 1.2 Generate the second random excitation 
              ! (i)  generate the first excited determinant  
              call create_excited_det_complete(cdet, connection_ki, cdet_excit)
              ! (ii) excite again
              call gen_excit_ptr(cdet_excit, Pgen_jk, connection_jk, hmatel_jk)
  
  
negative.code:         use determinants, only: det_info
          use excitations, only: excit
          use fciqmc_data, only: tau, H00
          use excitations, only: create_excited_det_complete, create_excited_det, get_excitation
          use basis, only: basis_length
  
          implicit none
          type(det_info), intent(in) :: cdet
          integer, intent(in) :: parent_sign
          integer, intent(out) :: nspawn
  