def test_exact_propagator(dt, space, shift):
prop_mpo = Mpo.exact_propagator(holstein_model, -1.0j * dt, space, shift)
with open(os.path.join(cur_dir, "test_exact_propagator.pickle"),
"rb") as fin:
std_dict = pickle.load(fin)
std_mpo = std_dict[space]
assert prop_mpo == std_mpo
def evolve_exact(self, h_mpo, evolve_dt, space):
MPOprop = Mpo.exact_propagator(self.model,
-1.0j * evolve_dt,
space=space,
shift=-h_mpo.offset)
# Mpdm is applied on the propagator, different from base method
new_mpdm = self.apply(MPOprop, canonicalise=True)
new_mpdm.coeff *= np.exp(-1.0j * h_mpo.offset * evolve_dt)
return new_mpdm
def evolve_exact(self, old_mpdm: MpDm, evolve_dt):
MPOprop = Mpo.exact_propagator(old_mpdm.model,
evolve_dt.imag,
space=self.space,
shift=-self.h_mpo.offset)
new_mpdm = MPOprop.apply(old_mpdm, canonicalise=True)
# partition function can't be obtained. It's not practical anyway.
# The function is too large to be fit into float64 even float128
new_mpdm.normalize(1.0)
return new_mpdm