anchor.diff:  
       end subroutine do_ccmc
   
  -    subroutine select_cluster(nattempts, D0_pos, cdet, cluster)
  +    subroutine select_cluster(nattempts, D0_pos, max_cluster_size, cdet, cluster)
   
           ! Select a random cluster of excitors from the excitors on the
           ! processor.  A cluster of excitors is itself an excitor.  For clarity
  
positive.code:         !    nattempts: the number of times (on this processor) a random cluster
          !        of excitors is generated in the current timestep.
          !    D0_pos: position in the excip list of the reference.
          ! In/Out:
          !    cdet: information about the cluster of excitors applied to the
          !        reference determinant.  This is a bare det_info variable on input
  
negative.code:         use utils, only: factorial
  
          integer(lint), intent(in) :: nattempts
          integer, intent(in) :: D0_pos, max_cluster_size
          type(det_info), intent(inout) :: cdet
          type(cluster_t), intent(inout) :: cluster
  
          real(p) :: rand, psize, psize_sum
          integer :: i, pos, cluster_population
  
          ! We shall accumulate the factors which comprise cluster%pselect as we go.
  