Coverage for gpaw/test/gllb/test_spin.py: 100%

1import pytest 

2from ase.build import bulk 

3 

4from gpaw import GPAW, FermiDirac 

5 

6 

7@pytest.mark.gllb 

8@pytest.mark.libxc 

9def test_gllb_spin(): 

10 for spin in [False, True]: 

11 a = 3.56 

12 atoms = bulk('C', 'diamond', a=a) 

13 calc = GPAW(mode='fd', 

14 kpts=(3, 3, 3), 

15 xc='GLLBSC', 

16 spinpol=spin, 

17 nbands=8, 

18 convergence={'bands': 6, 'density': 1e-6}, 

19 occupations=FermiDirac(width=0.005)) 

20 atoms.calc = calc 

21 atoms.get_potential_energy() 

22 resp = calc.hamiltonian.xc.response 

23 # Eks is the Kohn-Sham gap and Dxc is the derivative discontinuity 

24 if spin: 

25 homoa, lumoa = calc.get_homo_lumo(spin=0) 

26 homob, lumob = calc.get_homo_lumo(spin=1) 

27 dxc_pot = resp.calculate_discontinuity_potential((homoa, homob), 

28 (lumoa, lumob)) 

29 Eksa, Dxca = resp.calculate_discontinuity(dxc_pot, spin=0) 

30 Eksb, Dxcb = resp.calculate_discontinuity(dxc_pot, spin=1) 

31 Gapa = Eksa + Dxca 

32 Gapb = Eksb + Dxcb 

33 print("GAP", spin, Gapa, Gapb) 

34 else: 

35 homo, lumo = calc.get_homo_lumo() 

36 dxc_pot = resp.calculate_discontinuity_potential(homo, lumo) 

37 Eks, Dxc = resp.calculate_discontinuity(dxc_pot) 

38 Gap = Eks + Dxc 

39 print("GAP", spin, Gap) 

40 

41 assert Gapa == pytest.approx(Gapb, abs=1e-4) 

42 assert Gapa == pytest.approx(Gap, abs=1e-4)