anchor.diff:      type(rdm_spawn_t), allocatable :: rdm_spawn(:)
       ! The total number of rdms beings calculated.
       integer :: nrdms
  +    ! The length of the spawning array for RDMs. Each RDM calculated has the same
  +    ! length array.
  +    integer :: spawned_rdm_length
       ! This stores all the information for the various RDMs that the user asks
       ! to be calculated. Each element of this array corresponds to one of these RDMs.
       type(rdm_t), allocatable :: rdms(:)
  
positive.code: ! They are thrown away after these calculation has been performed on them.
  logical :: calc_inst_rdm = .false.
  
  ! The length of the spawning array for RDMs. Each RDM calculated has the same
  ! length array.
  integer :: spawned_rdm_length
  
  ! If true then calculate the concurrence for reduced density matrix of two sites.
  logical :: doing_concurrence = .false.
  
  
negative.code:     integer :: beta_loops = 100
      ! timestep
      real(p) :: tau
      ! projected energy
      ! This stores during an FCIQMC report loop
      !   \sum_{i/=0} <D_0|H|D_i> N_i
  