anchor.diff:          type(det_info), intent(in) :: cdet
   
           real(dp) :: pgen, psuccess, pspawn
  -        integer :: i, j, a, b, ij_sym, ab_sym, nparticles
  +        integer :: i, j, a, b, ij_sym, ab_sym, nparticles, s
           integer(i0) :: f_new(basis_length)
           type(excit) :: connection
   
  
positive.code:         ! See choose_ij_hub_k for a specific procedure for the momentum space
          ! formulation of the hubbard model.
          ! In:
          !    occ_list: Integer list of occupied spin-orbitals.
          ! Out:
          !    i, j: randomly selected spin-orbitals.
          !    ij_sym: symmetry label of the (i,j) combination.
  
negative.code:         ! and p_select = p_gen for normalised probabilities.
          ! p_select is included intrinsically in the algorithm, so we compare
          ! to the probability tau*|H_ij|/p_gen.
          ! As we can only excite from (alpha,beta) or (beta,alpha),
          !   H_ij =  < ij | ab >  *or*
          !        = -< ij | ba >
          ! so
          !   |H_ij| = U/\Omega
          ! for allowed excitations.
          pspawn = tau*hub_k_coulomb/pgen
          psuccess = genrand_real2()
  
  