Coverage for gpaw/test/directopt/test_break_instability_lcao.py: 100%

1import pytest 

2 

3from gpaw import GPAW 

4from gpaw.directmin.derivatives import Davidson 

5 

6 

7@pytest.mark.old_gpaw_only 

8@pytest.mark.do 

9def test_break_instability_lcao(in_tmp_dir, gpw_files): 

10 calc = GPAW(gpw_files['h2_break_ilcao']) 

11 # XXX(rg): Remove hack after tchem-gl-13 

12 calc.set_positions() 

13 calc.wfs.eigensolver.initialize_dm_helper(calc.wfs, 

14 calc.hamiltonian, 

15 calc.density, 

16 calc.log) 

17 atoms = calc.atoms 

18 atoms.calc = calc 

19 e_symm = atoms.get_potential_energy() 

20 assert e_symm == pytest.approx(-2.035632, abs=1.0e-3) 

21 

22 davidson = Davidson(calc.wfs.eigensolver, None, seed=42) 

23 davidson.run(calc.wfs, calc.hamiltonian, calc.density) 

24 

25 # Break the instability by displacing along the eigenvector of the 

26 # electronic Hessian corresponding to the negative eigenvalue 

27 C_ref = [calc.wfs.kpt_u[x].C_nM.copy() 

28 for x in range(len(calc.wfs.kpt_u))] 

29 davidson.break_instability(calc.wfs, n_dim=[10, 10], 

30 c_ref=C_ref, number=1) 

31 

32 calc.calculate(properties=['energy'], system_changes=['positions']) 

33 e_bsymm = atoms.get_potential_energy() 

34 assert e_bsymm == pytest.approx(-2.418488, abs=1.0e-3)