Coverage for gpaw/test/ext_potential/test_external.py: 93%

1import pytest 

2from ase import Atoms 

3 

4from gpaw import GPAW 

5from gpaw.external import ConstantPotential 

6 

7 

8@pytest.mark.old_gpaw_only 

9def test_ext_potential_external(): 

10 sc = 2.9 

11 R = 0.7 # approx. experimental bond length 

12 R = 1.0 

13 a = 2 * sc 

14 c = 3 * sc 

15 H2 = Atoms('HH', [(a / 2, a / 2, (c - R) / 2), 

16 (a / 2, a / 2, (c + R) / 2)], 

17 cell=(a, a, c), 

18 pbc=False) 

19 

20 txt = None 

21 

22 convergence = {'eigenstates': 1.e-4 * 40 * 1.5**3, 

23 'density': 1.e-2, 

24 'energy': 0.1} 

25 

26 # without potential 

27 if True: 

28 if txt: 

29 print('\n################## no potential') 

30 c00 = GPAW(mode='fd', h=0.3, nbands=-1, 

31 convergence=convergence, 

32 txt=txt) 

33 c00.calculate(H2) 

34 c00.get_eigenvalues() 

35 

36 # 0 potential 

37 if True: 

38 if txt: 

39 print('\n################## 0 potential') 

40 cp0 = ConstantPotential(0.0) 

41 c01 = GPAW(mode='fd', h=0.3, nbands=-2, external=cp0, 

42 convergence=convergence, 

43 txt=txt) 

44 c01.calculate(H2) 

45 

46 # 1 potential 

47 if True: 

48 if txt: 

49 print('################## 1 potential') 

50 cp1 = ConstantPotential(-1.0) 

51 c1 = GPAW(mode='fd', h=0.3, nbands=-2, external=cp1, 

52 convergence=convergence, 

53 txt=txt) 

54 c1.calculate(H2) 

55 

56 for i in range(c00.get_number_of_bands()): 

57 f00 = c00.get_occupation_numbers()[i] 

58 if f00 > 0.01: 

59 e00 = c00.get_eigenvalues()[i] 

60 e1 = c1.get_eigenvalues()[i] 

61 print('Eigenvalues no pot, expected, error=', 

62 e00, e1 + 1, e00 - e1 - 1) 

63 assert e00 == pytest.approx(e1 + 1., abs=0.008) 

64 

65 E_c00 = c00.get_potential_energy() 

66 E_c1 = c1.get_potential_energy() 

67 DeltaE = E_c00 - E_c1 

68 assert DeltaE == pytest.approx(0, abs=0.002)