anchor.diff:          !        and the child determinant, on which progeny are spawned.
           use determinants, only: det_info
           use excitations, only: excit
  -        use fciqmc_data, only: tau
  +        use fciqmc_data, only: tau, H00
           use excitations, only: create_excited_det_complete
   
           type(det_info), intent(in) :: cdet
  
positive.code:             call create_excited_det_complete(cdet, connection_ki, cdet_excit) !could optimise this with create_excited det - we only need %f
              ! (ii) calculate Pgen and hmatel on this site       
              Pgen_jk = 1
              hmatel_jk =  sc0_ptr(cdet_excit%f) - fold_line !***optimise this with stored/calculated values
              
              ! 2. Probability of gening...
              pgen = P_o * Pgen_ki * Pgen_jk
  
negative.code:             connection%nexcit = connection_ki%nexcit + connection_jk%nexcit
              ! (ii)  combine the annihilations
              connection%from_orb(:connection_ki%nexcit) = &
                                  connection_ki%from_orb(:connection_ki%nexcit)
  
              connection%from_orb(connection_ki%nexcit+1:connection%nexcit) = &
                                  connection_jk%from_orb(:connection_jk%nexcit)
  
              ! (iii) combine the creations
              connection%to_orb(:connection_ki%nexcit) = &
  