anchor.diff:  
           ! 3. Attempt spawning.
           nspawn = attempt_to_spawn(hmatel, pgen, parent_sign)
  +
  +        if (nspawn /= 0) then
  +            ! 4. Convert the random excitation from a determinant into an
  +            ! excitor.  This might incur a sign change and hence result in
  +            ! a change in sign to the sign of the progeny.
  +            ! This is the same process as excitor to determinant and hence we
  +            ! can reuse code...
  +            call create_excited_det(cdet%f, connection, fexcit)
  +            excitor_level = get_excitation_level(f0, fexcit)
  +            excitor_sign = 1
  +            call convert_excitor_to_determinant(fexcit, excitor_level, excitor_sign)
  +            if (excitor_sign < 0) nspawn = -nspawn
  +        end if
   
       end subroutine spawner_ccmc
   
  
positive.code:         !    connection: excitation connection between the current excitor
          !        and the child excitor, on which progeny are spawned.
  
          use determinants, only: det_info
          use excitations, only: excit
          use proc_pointers, only: gen_excit_ptr
          use spawning, only: attempt_to_spawn
  
  
negative.code:         ! actually spawned by positive excips.
          integer, parameter :: parent_sign = 1
          real(p) :: hmatel, pgen
          integer(i0) :: fexcit(basis_length)
          integer :: excitor_sign, excitor_level
  
          ! 1. Generate random excitation.
          ! Note CCMC is not (yet, if ever) compatible with the 'split' excitation
  