code: def compute_partial_energy(self, removed_indices):
          
          total_energy_matrix = self.total_energy_matrix.copy()
          for i in removed_indices:
              total_energy_matrix[i, :] = 0
              total_energy_matrix[:, i] = 0
          return sum(sum(total_energy_matrix))
docs: Gives total ewald energy for certain sites being removed, i.e. zeroed
          out.