Coverage for gpaw/test/response/test_hchain_supercell.py: 100%

1# Test of the handling of degenerate bands in response code 

2import pytest 

3from ase import Atoms 

4from gpaw import GPAW, PW 

5from gpaw.response.df import DielectricFunction 

6from gpaw.test import findpeak 

7import numpy as np 

8 

9 

10def get_hydrogen_chain_dielectric_function(NH, NK): 

11 a = Atoms('H', cell=[1, 1, 2], pbc=True) 

12 a.center() 

13 a = a.repeat((1, 1, NH)) 

14 a.calc = GPAW(mode=PW(200, force_complex_dtype=True), 

15 kpts={'size': (1, 1, NK), 'gamma': True}, 

16 parallel={'band': 1}, 

17 gpts=(10, 10, 10 * NH)) 

18 a.get_potential_energy() 

19 a.calc.diagonalize_full_hamiltonian(nbands=2 * NH) 

20 a.calc.write('H_chain.gpw', 'all') 

21 

22 DF = DielectricFunction('H_chain.gpw', ecut=1e-3, hilbert=False, 

23 frequencies={'type': 'nonlinear', 

24 'domega0': None, 

25 'omega2': np.inf, 

26 'omegamax': None}, 

27 intraband=False) 

28 eps_NLF, eps_LF = DF.get_dielectric_function(direction='z') 

29 omega_w = DF.get_frequencies() 

30 return omega_w, eps_LF 

31 

32 

33@pytest.mark.dielectricfunction 

34@pytest.mark.serial 

35@pytest.mark.response 

36def test_hyd_chain_response(in_tmp_dir): 

37 NH_i = [2**n for n in [0, 2]] 

38 NK_i = [2**n for n in [4, 2]] 

39 

40 opeak_old = np.nan 

41 peak_old = np.nan 

42 

43 for NH, NK in zip(NH_i, NK_i): 

44 omega_w, eps_w = get_hydrogen_chain_dielectric_function(NH, NK) 

45 eels_w = -(1. / eps_w).imag 

46 opeak, peak = findpeak(omega_w, eels_w) 

47 

48 # Test for consistency 

49 if not np.isnan(opeak_old): 

50 assert opeak == pytest.approx(opeak_old, abs=1e-3) 

51 assert peak == pytest.approx(peak_old, abs=1e-3) 

52 opeak_old = opeak 

53 peak_old = peak