def test_adc2_shift_invert_triplets(self):
refdata = cache.reference_data["h2o_sto3g"]
matrix = adcc.AdcMatrix("adc2", LazyMp(cache.refstate["h2o_sto3g"]))
conv_tol = 1e-5
shift = -0.5
# Construct shift and inverted matrix:
shinv = IterativeInverse(AdcMatrixShifted(matrix, shift),
conv_tol=conv_tol / 10,
Pinv=JacobiPreconditioner,
callback=cg_print)
# Solve for triplets
guesses = adcc.guesses_triplet(matrix, n_guesses=5, block="ph")
symm = IndexSpinSymmetrisation(matrix, enforce_spin_kind="triplet")
res = lanczos(shinv,
guesses,
n_ep=5,
callback=la_print,
explicit_symmetrisation=symm)
assert res.converged
# Undo spectral transformation and compare
eigenvalues = sorted(1 / res.eigenvalues - shift)
ref_triplets = refdata["adc2"]["triplet"]["eigenvalues"][:5]
assert eigenvalues == approx(ref_triplets)
def base_adc2(self, kind, guess_function, max_iter=100):
refdata = cache.reference_data["h2o_sto3g"]
matrix = adcc.AdcMatrix("adc2", cache.refstate["h2o_sto3g"])
conv_tol = 1e-6
guesses = guess_function(matrix, n_guesses=1)
symm = IndexSpinSymmetrisation(matrix, enforce_spin_kind=kind)
inverse = IterativeInverse(matrix,
Pinv=JacobiPreconditioner,
conv_tol=conv_tol / 10,
construct_guess=guess_from_previous)
res = power_method(inverse,
guesses[0],
conv_tol=conv_tol,
explicit_symmetrisation=symm,
callback=powprint,
max_iter=max_iter)
ref_singlets = refdata["adc2"][kind]["eigenvalues"]
assert res.converged
assert 1 / res.eigenvalues[0] == approx(ref_singlets[0])