Coverage for gpaw/test/hubbard/test_hubbard_U.py: 100%

1from math import sqrt 

2 

3from ase import Atoms 

4from ase.dft.bandgap import bandgap 

5 

6from gpaw import GPAW, FermiDirac 

7import pytest 

8 

9 

10def test_Hubbard_U(in_tmp_dir): 

11 """Setup up bulk NiO in an antiferromagnetic configuration.""" 

12 # Lattice constant: 

13 a = 4.19 

14 b = a / sqrt(2) 

15 

16 m = 2 

17 k = 2 # number of k-points 

18 

19 atoms = Atoms( 

20 symbols='Ni2O2', 

21 pbc=True, 

22 cell=(b, b, a), 

23 positions=[(0, 0, 0), 

24 (b / 2, b / 2, a / 2), 

25 (0, 0, a / 2), 

26 (b / 2, b / 2, 0)], 

27 magmoms=(m, -m, 0, 0)) 

28 

29 name = 'ni2o2' 

30 for setup in ['10', '10:d,6.0']: 

31 calc = GPAW( 

32 mode='pw', 

33 occupations=FermiDirac(width=0.05), 

34 setups={'Ni': setup}, 

35 convergence={'eigenstates': 8e-4, 

36 'density': 1.0e-2, 

37 'energy': 0.1}, 

38 txt=name + '.txt', 

39 kpts=(k, k, k), 

40 xc='oldPBE') 

41 atoms.calc = calc 

42 atoms.get_potential_energy() 

43 gap, _, _ = bandgap(calc) 

44 print(name, gap) 

45 if name == 'ni2o2': 

46 assert gap == pytest.approx(0.8, abs=0.1) 

47 else: 

48 assert gap == pytest.approx(4.7, abs=0.2) 

49 name += '+U'