code: def nearest_neighbour_delta_E( self ):
          
          delta_nn = self.final_site.nn_occupation() - self.initial_site.nn_occupation() - 1 # -1 because the hopping ion is not counted in the final site occupation number
          return ( delta_nn * self.nearest_neighbour_energy )
docs: Nearest-neighbour interaction contribution to the change in system energy if this jump were accepted.
  
          Args:
              None
  
          Returns:
              (Float): delta E (nearest-neighbour)