class PhaseDiagramTest(unittest.TestCase):
def setUp(self):
self.entries = EntrySet.from_csv(str(module_dir /
"pdentries_test.csv"))
self.pd = PhaseDiagram(self.entries)
warnings.simplefilter("ignore")
def tearDown(self):
warnings.simplefilter("default")
def test_init(self):
# Ensure that a bad set of entries raises a PD error. Remove all Li
# from self.entries.
entries = filter(
lambda e: (not e.composition.is_element) or e.composition.elements[
0] != Element("Li"),
self.entries,
)
self.assertRaises(PhaseDiagramError, PhaseDiagram, entries)
def test_dim1(self):
# Ensure that dim 1 PDs can eb generated.
for el in ["Li", "Fe", "O2"]:
entries = [
e for e in self.entries if e.composition.reduced_formula == el
]
pd = PhaseDiagram(entries)
self.assertEqual(len(pd.stable_entries), 1)
for e in entries:
decomp, ehull = pd.get_decomp_and_e_above_hull(e)
self.assertGreaterEqual(ehull, 0)
plotter = PDPlotter(pd)
lines, stable_entries, unstable_entries = plotter.pd_plot_data
self.assertEqual(lines[0][1], [0, 0])
def test_ordering(self):
# Test sorting of elements
entries = [
ComputedEntry(Composition(formula), 0)
for formula in ["O", "N", "Fe"]
]
pd = PhaseDiagram(entries)
sorted_elements = (Element("Fe"), Element("N"), Element("O"))
self.assertEqual(tuple(pd.elements), sorted_elements)
entries.reverse()
pd = PhaseDiagram(entries)
self.assertEqual(tuple(pd.elements), sorted_elements)
# Test manual specification of order
ordering = [Element(elt_string) for elt_string in ["O", "N", "Fe"]]
pd = PhaseDiagram(entries, elements=ordering)
self.assertEqual(tuple(pd.elements), tuple(ordering))
def test_stable_entries(self):
stable_formulas = [
ent.composition.reduced_formula for ent in self.pd.stable_entries
]
expected_stable = [
"Fe2O3",
"Li5FeO4",
"LiFeO2",
"Fe3O4",
"Li",
"Fe",
"Li2O",
"O2",
"FeO",
]
for formula in expected_stable:
self.assertTrue(formula in stable_formulas,
formula + " not in stable entries!")
def test_get_formation_energy(self):
stable_formation_energies = {
ent.composition.reduced_formula: self.pd.get_form_energy(ent)
for ent in self.pd.stable_entries
}
expected_formation_energies = {
"Li5FeO4": -164.8117344866667,
"Li2O2": -14.119232793333332,
"Fe2O3": -16.574164339999996,
"FeO": -5.7141519966666685,
"Li": 0.0,
"LiFeO2": -7.732752316666666,
"Li2O": -6.229303868333332,
"Fe": 0.0,
"Fe3O4": -22.565714456666683,
"Li2FeO3": -45.67166036000002,
"O2": 0.0,
}
for formula, energy in expected_formation_energies.items():
self.assertAlmostEqual(energy, stable_formation_energies[formula],
7)
def test_all_entries_hulldata(self):
self.assertEqual(len(self.pd.all_entries_hulldata), 492)
def test_planar_inputs(self):
e1 = PDEntry("H", 0)
e2 = PDEntry("He", 0)
e3 = PDEntry("Li", 0)
e4 = PDEntry("Be", 0)
e5 = PDEntry("B", 0)
e6 = PDEntry("Rb", 0)
pd = PhaseDiagram([e1, e2, e3, e4, e5, e6],
map(Element, ["Rb", "He", "B", "Be", "Li", "H"]))
self.assertEqual(len(pd.facets), 1)
def test_str(self):
self.assertIsNotNone(str(self.pd))
def test_get_e_above_hull(self):
for entry in self.pd.stable_entries:
self.assertLess(
self.pd.get_e_above_hull(entry),
1e-11,
"Stable entries should have e above hull of zero!",
)
for entry in self.pd.all_entries:
if entry not in self.pd.stable_entries:
e_ah = self.pd.get_e_above_hull(entry)
self.assertTrue(isinstance(e_ah, Number))
self.assertGreaterEqual(e_ah, 0)
def test_get_equilibrium_reaction_energy(self):
for entry in self.pd.stable_entries:
self.assertLessEqual(
self.pd.get_equilibrium_reaction_energy(entry),
0,
"Stable entries should have negative equilibrium reaction energy!",
)
def test_get_quasi_e_to_hull(self):
for entry in self.pd.unstable_entries:
# catch duplicated stable entries
if entry.normalize(
inplace=False) in self.pd.get_stable_entries_normed():
self.assertLessEqual(
self.pd.get_quasi_e_to_hull(entry),
0,
"Duplicated stable entries should have negative decomposition energy!",
)
else:
self.assertGreaterEqual(
self.pd.get_quasi_e_to_hull(entry),
0,
"Unstable entries should have positive decomposition energy!",
)
for entry in self.pd.stable_entries:
if entry.composition.is_element:
self.assertEqual(
self.pd.get_quasi_e_to_hull(entry),
0,
"Stable elemental entries should have decomposition energy of zero!",
)
else:
self.assertLessEqual(
self.pd.get_quasi_e_to_hull(entry),
0,
"Stable entries should have negative decomposition energy!",
)
novel_stable_entry = PDEntry("Li5FeO4", -999)
self.assertLess(
self.pd.get_quasi_e_to_hull(novel_stable_entry),
0,
"Novel stable entries should have negative decomposition energy!",
)
novel_unstable_entry = PDEntry("Li5FeO4", 999)
self.assertGreater(
self.pd.get_quasi_e_to_hull(novel_unstable_entry),
0,
"Novel unstable entries should have positive decomposition energy!",
)
duplicate_entry = PDEntry("Li2O", -14.31361175)
scaled_dup_entry = PDEntry("Li4O2", -14.31361175 * 2)
stable_entry = [e for e in self.pd.stable_entries
if e.name == "Li2O"][0]
self.assertEqual(
self.pd.get_quasi_e_to_hull(duplicate_entry),
self.pd.get_quasi_e_to_hull(stable_entry),
"Novel duplicates of stable entries should have same decomposition energy!",
)
self.assertEqual(
self.pd.get_quasi_e_to_hull(scaled_dup_entry),
self.pd.get_quasi_e_to_hull(stable_entry),
"Novel scaled duplicates of stable entries should have same decomposition energy!",
)
def test_get_decomposition(self):
for entry in self.pd.stable_entries:
self.assertEqual(
len(self.pd.get_decomposition(entry.composition)),
1,
"Stable composition should have only 1 decomposition!",
)
dim = len(self.pd.elements)
for entry in self.pd.all_entries:
ndecomp = len(self.pd.get_decomposition(entry.composition))
self.assertTrue(
ndecomp > 0 and ndecomp <= dim,
"The number of decomposition phases can at most be equal to the number of components.",
)
# Just to test decomp for a ficitious composition
ansdict = {
entry.composition.formula: amt
for entry, amt in self.pd.get_decomposition(
Composition("Li3Fe7O11")).items()
}
expected_ans = {
"Fe2 O2": 0.0952380952380949,
"Li1 Fe1 O2": 0.5714285714285714,
"Fe6 O8": 0.33333333333333393,
}
for k, v in expected_ans.items():
self.assertAlmostEqual(ansdict[k], v)
def test_get_transition_chempots(self):
for el in self.pd.elements:
self.assertLessEqual(len(self.pd.get_transition_chempots(el)),
len(self.pd.facets))
def test_get_element_profile(self):
for el in self.pd.elements:
for entry in self.pd.stable_entries:
if not (entry.composition.is_element):
self.assertLessEqual(
len(self.pd.get_element_profile(el,
entry.composition)),
len(self.pd.facets),
)
expected = [
{
"evolution": 1.0,
"chempot": -4.2582781416666666,
"reaction": "Li2O + 0.5 O2 -> Li2O2",
},
{
"evolution": 0,
"chempot": -5.0885906699999968,
"reaction": "Li2O -> Li2O",
},
{
"evolution": -1.0,
"chempot": -10.487582010000001,
"reaction": "Li2O -> 2 Li + 0.5 O2",
},
]
result = self.pd.get_element_profile(Element("O"), Composition("Li2O"))
for d1, d2 in zip(expected, result):
self.assertAlmostEqual(d1["evolution"], d2["evolution"])
self.assertAlmostEqual(d1["chempot"], d2["chempot"])
self.assertEqual(d1["reaction"], str(d2["reaction"]))
def test_get_get_chempot_range_map(self):
elements = [el for el in self.pd.elements if el.symbol != "Fe"]
self.assertEqual(len(self.pd.get_chempot_range_map(elements)), 10)
def test_getmu_vertices_stability_phase(self):
results = self.pd.getmu_vertices_stability_phase(
Composition("LiFeO2"), Element("O"))
self.assertAlmostEqual(len(results), 6)
test_equality = False
for c in results:
if (abs(c[Element("O")] + 7.115) < 1e-2
and abs(c[Element("Fe")] + 6.596) < 1e-2
and abs(c[Element("Li")] + 3.931) < 1e-2):
test_equality = True
self.assertTrue(test_equality,
"there is an expected vertex missing in the list")
def test_getmu_range_stability_phase(self):
results = self.pd.get_chempot_range_stability_phase(
Composition("LiFeO2"), Element("O"))
self.assertAlmostEqual(results[Element("O")][1], -4.4501812249999997)
self.assertAlmostEqual(results[Element("Fe")][0], -6.5961470999999996)
self.assertAlmostEqual(results[Element("Li")][0], -3.6250022625000007)
def test_get_hull_energy(self):
for entry in self.pd.stable_entries:
h_e = self.pd.get_hull_energy(entry.composition)
self.assertAlmostEqual(h_e, entry.energy)
n_h_e = self.pd.get_hull_energy(
entry.composition.fractional_composition)
self.assertAlmostEqual(n_h_e, entry.energy_per_atom)
def test_1d_pd(self):
entry = PDEntry("H", 0)
pd = PhaseDiagram([entry])
decomp, e = pd.get_decomp_and_e_above_hull(PDEntry("H", 1))
self.assertAlmostEqual(e, 1)
self.assertAlmostEqual(decomp[entry], 1.0)
def test_get_critical_compositions_fractional(self):
c1 = Composition("Fe2O3").fractional_composition
c2 = Composition("Li3FeO4").fractional_composition
c3 = Composition("Li2O").fractional_composition
comps = self.pd.get_critical_compositions(c1, c2)
expected = [
Composition("Fe2O3").fractional_composition,
Composition("Li0.3243244Fe0.1621621O0.51351349"),
Composition("Li3FeO4").fractional_composition,
]
for crit, exp in zip(comps, expected):
self.assertTrue(crit.almost_equals(exp, rtol=0, atol=1e-5))
comps = self.pd.get_critical_compositions(c1, c3)
expected = [
Composition("Fe0.4O0.6"),
Composition("LiFeO2").fractional_composition,
Composition("Li5FeO4").fractional_composition,
Composition("Li2O").fractional_composition,
]
for crit, exp in zip(comps, expected):
self.assertTrue(crit.almost_equals(exp, rtol=0, atol=1e-5))
def test_get_critical_compositions(self):
c1 = Composition("Fe2O3")
c2 = Composition("Li3FeO4")
c3 = Composition("Li2O")
comps = self.pd.get_critical_compositions(c1, c2)
expected = [
Composition("Fe2O3"),
Composition("Li0.3243244Fe0.1621621O0.51351349") * 7.4,
Composition("Li3FeO4"),
]
for crit, exp in zip(comps, expected):
self.assertTrue(crit.almost_equals(exp, rtol=0, atol=1e-5))
comps = self.pd.get_critical_compositions(c1, c3)
expected = [
Composition("Fe2O3"),
Composition("LiFeO2"),
Composition("Li5FeO4") / 3,
Composition("Li2O"),
]
for crit, exp in zip(comps, expected):
self.assertTrue(crit.almost_equals(exp, rtol=0, atol=1e-5))
# Don't fail silently if input compositions aren't in phase diagram
# Can be very confusing if you're working with a GrandPotentialPD
self.assertRaises(
ValueError,
self.pd.get_critical_compositions,
Composition("Xe"),
Composition("Mn"),
)
# For the moment, should also fail even if compositions are in the gppd
# because it isn't handled properly
gppd = GrandPotentialPhaseDiagram(self.pd.all_entries, {"Xe": 1},
self.pd.elements + [Element("Xe")])
self.assertRaises(
ValueError,
gppd.get_critical_compositions,
Composition("Fe2O3"),
Composition("Li3FeO4Xe"),
)
# check that the function still works though
comps = gppd.get_critical_compositions(c1, c2)
expected = [
Composition("Fe2O3"),
Composition("Li0.3243244Fe0.1621621O0.51351349") * 7.4,
Composition("Li3FeO4"),
]
for crit, exp in zip(comps, expected):
self.assertTrue(crit.almost_equals(exp, rtol=0, atol=1e-5))
# case where the endpoints are identical
self.assertEqual(self.pd.get_critical_compositions(c1, c1 * 2),
[c1, c1 * 2])
def test_get_composition_chempots(self):
c1 = Composition("Fe3.1O4")
c2 = Composition("Fe3.2O4.1Li0.01")
e1 = self.pd.get_hull_energy(c1)
e2 = self.pd.get_hull_energy(c2)
cp = self.pd.get_composition_chempots(c1)
calc_e2 = e1 + sum(cp[k] * v for k, v in (c2 - c1).items())
self.assertAlmostEqual(e2, calc_e2)
def test_get_all_chempots(self):
c1 = Composition("Fe3.1O4")
c2 = Composition("FeO")
cp1 = self.pd.get_all_chempots(c1)
cpresult = {
Element("Li"): -4.077061954999998,
Element("Fe"): -6.741593864999999,
Element("O"): -6.969907375000003,
}
for elem, energy in cpresult.items():
self.assertAlmostEqual(cp1["Fe3O4-FeO-LiFeO2"][elem], energy)
cp2 = self.pd.get_all_chempots(c2)
cpresult = {
Element("O"): -7.115354140000001,
Element("Fe"): -6.5961471,
Element("Li"): -3.9316151899999987,
}
for elem, energy in cpresult.items():
self.assertAlmostEqual(cp2["FeO-LiFeO2-Fe"][elem], energy)
def test_to_from_dict(self):
# test round-trip for other entry types such as ComputedEntry
entry = ComputedEntry("H", 0.0, 0.0, entry_id="test")
pd = PhaseDiagram([entry])
d = pd.as_dict()
pd_roundtrip = PhaseDiagram.from_dict(d)
self.assertEqual(pd.all_entries[0].entry_id,
pd_roundtrip.all_entries[0].entry_id)
def __init__(self, material_id, vasprun_dict, ref_element,
exclude_ids=[], custom_entries=[], mapi_key=None):
"""
Analyzes surface energies and Wulff shape of a particular
material using the chemical potential.
Args:
material_id (str): Materials Project material_id (a string,
e.g., mp-1234).
vasprun_dict (dict): Dictionary containing a list of Vaspruns
for slab calculations as items and the corresponding Miller
index of the slab as the key.
eg. vasprun_dict = {(1,1,1): [vasprun_111_1, vasprun_111_2,
vasprun_111_3], (1,1,0): [vasprun_111_1, vasprun_111_2], ...}
element: element to be considered as independent
variables. E.g., if you want to show the stability
ranges of all Li-Co-O phases wrt to uLi
exclude_ids (list of material_ids): List of material_ids
to exclude when obtaining the decomposition components
to calculate the chemical potential
custom_entries (list of pymatgen-db type entries): List of
user specified pymatgen-db type entries to use in finding
decomposition components for the chemical potential
mapi_key (str): Materials Project API key for accessing the
MP database via MPRester
"""
self.ref_element = ref_element
self.mprester = MPRester(mapi_key) if mapi_key else MPRester()
self.ucell_entry = \
self.mprester.get_entry_by_material_id(material_id,
inc_structure=True,
property_data=
["formation_energy_per_atom"])
ucell = self.ucell_entry.structure
# Get x and y, the number of species in a formula unit of the bulk
reduced_comp = ucell.composition.reduced_composition.as_dict()
if len(reduced_comp.keys()) == 1:
x = y = reduced_comp[ucell[0].species_string]
else:
for el in reduced_comp.keys():
if self.ref_element == el:
y = reduced_comp[el]
else:
x = reduced_comp[el]
# Calculate Gibbs free energy of the bulk per unit formula
gbulk = self.ucell_entry.energy /\
(len([site for site in ucell
if site.species_string == self.ref_element]) / y)
entries = [entry for entry in
self.mprester.get_entries_in_chemsys(list(reduced_comp.keys()),
property_data=["e_above_hull",
"material_id"])
if entry.data["e_above_hull"] == 0 and
entry.data["material_id"] not in exclude_ids] \
if not custom_entries else custom_entries
pd = PhaseDiagram(entries)
chempot_ranges = pd.get_chempot_range_map([Element(self.ref_element)])
# If no chemical potential is found, we return u=0, eg.
# for a elemental system, the relative u of Cu for Cu is 0
chempot_range = [chempot_ranges[entry] for entry in chempot_ranges.keys()
if entry.composition ==
self.ucell_entry.composition][0][0]._coords if \
chempot_ranges else [[0,0], [0,0]]
e_of_element = [entry.energy_per_atom for entry in
entries if str(entry.composition.reduced_composition)
== self.ref_element + "1"][0]
self.x = x
self.y = y
self.gbulk = gbulk
chempot_range = list(chempot_range)
self.chempot_range = sorted([chempot_range[0][0], chempot_range[1][0]])
self.e_of_element = e_of_element
self.vasprun_dict = vasprun_dict
