def test_potential_annihilation(self):
        #add particles
        particle_list = [
            (4, 1,  0, espressopp.Real3D(2.0, 2.0, 2.0), 1.0, 0),
            (5, 1,  0, espressopp.Real3D(2.3, 2.0, 2.0), 1.0, 0),