anchor.diff:  ! [review] - NSB: logically. I've created derived types for ground-state RDMs and
   ! [review] - NSB: instantaneous RDMs, and for the weighted sampling.
   ! [review] - JSS: split this into input-level data and calculation-derived data.
  +! [review] - NSB: Agree, will do.
   type dmqmc_estimates_t
       ! [review] - NSB: dmqmc_factor is a bit of a wierd one because it is used more
       ! [review] - NSB: more generally by other methods, too. It is just a number
  
positive.code:     ! be normalised by the product of the corresponding RDM traces.
      ! call it y. Then the renyi-2 entropy is then given by -log_2(x/y).
      ! [review] - JSS: dimensions?
      real(p), allocatable :: renyi_2(:)
  
      real(p), allocatable :: excit_distribution(:) ! (0:max_number_excitations)
  
negative.code: 
  !--- Folded spectrum data ---
  ! [review] - JSS: input options (also, should we just delete folded spectrum?)
  ! [review] - NSB: I wouldn't mind, but I'll have to leave it up to you.
  type folded_spect_t
      ! The line about which you are folding i.e. eps in (H-eps)^2 - E_0
      real(p) :: fold_line = 0
  