anchor.diff:      integer, allocatable :: correlation_sites(:)
   end type dmqmc_t
   
  +! [review] - FDM: Not sure where this belongs.
   ! When using the Neel singlet trial wavefunction, it is convenient
   ! to store all possible amplitudes in the wavefunction, since
   ! there are relativley few of them and they are expensive to calculate
   real(dp), allocatable :: neel_singlet_amp(:) ! (nsites/2) + 1
   
  +! [review] - FDM: Not sure where this belongs (spawned_walkers / walkers?).
   real(dp) :: annihilation_comms_time = 0.0_dp
   
   !--- Folded spectrum data ---
  
positive.code:     real(p) :: spawn_cutoff = 0.01_p
  end type walker_t
  
  type spawned_walker_t
      ! Array sizes
      ! If these are < 0, then the values represent the number of MB to be used to
  
negative.code:     ! Population above which a determinant is an initiator.
      real(p) :: initiator_population = 3.0_p
  end type initiator_t
  
  ! [review] - FDM: Should determ_hash_t and semi_stoch_t be in semi_stoch.F90?
  
  ! Array to hold the indices of deterministic states in the dets array, accessed
  ! by calculating a hash value. This type is used by the semi_stoch_t type and
  