anchor.diff:  ! See documentation/theory/hellmann_feynman/hf.tex for details.
   
   use const
  -
  -use hfs_data
  -
  -use proc_pointers
   
   implicit none
   
  
positive.code:                         ! Attempt to spawn Hamiltonian walkers..
                          call spawner_ptr(cdet, walker_population(1,idet), nspawned, connection)
                          ! Spawn if attempt was successful.
                          if (nspawned /= 0) call create_spawned_particle(cdet, connection, nspawned, spawned_pop)
  
                          ! Attempt to spawn Hellmann--Feynman walkers from
                          ! Hamiltonian walkers.
                          call spawner_hfs_ptr(cdet, walker_population(1,idet), nspawned, connection)
                          ! Spawn if attempt was successful.
                          if (nspawned /= 0) call create_spawned_particle(cdet, connection, nspawned, spawned_hf_pop)
  
                      end do
  
  
negative.code:                         ! Hellmann--Feynman walkers.
                          call spawner_ptr(cdet, walker_population(2,idet), nspawned, connection)
                          ! Spawn if attempt was successful.
                          if (nspawned /= 0) call create_spawned_particle_ptr(cdet, connection, nspawned, spawned_hf_pop)
  
                      end do
  
  