def atoms_no_pbc():
ref_atoms = Icosahedron('Ag', 2, 3.82975)
ref_atoms.calc = EMT()
atoms = ref_atoms.copy()
atoms.calc = EMT()
atoms.rattle(stdev=0.1, seed=7)
e_unopt = atoms.get_potential_energy()
assert e_unopt > 7 # it's 7.318 as of writing this test
return atoms, ref_atoms
