def test_model_H_conversion(L=6):
bc = 'finite'
model_params = {'L': L, 'hz': np.random.random([L]), 'bc_MPS': bc}
m = XXZChain(model_params)
# can we run the conversion?
# conversion from bond to MPO in NearestNeighborModel
H_MPO = m.calc_H_MPO_from_bond()
# conversion from MPO to bond in MPOModel
H_bond = m.calc_H_bond_from_MPO()
# compare: did we get the correct result?
ED = ExactDiag(m)
ED.build_full_H_from_bonds()
H0 = ED.full_H # this should be correct
ED.full_H = None
m.H_MPO = H_MPO
ED.build_full_H_from_mpo()
full_H_mpo = ED.full_H # the one generated by NearstNeighborModel.calc_H_MPO_from_bond()
print("npc.norm(H0 - full_H_mpo) = ", npc.norm(H0 - full_H_mpo))
assert npc.norm(H0 -
full_H_mpo) < 1.e-14 # round off errors on order of 1.e-15
m.H_bond = H_bond
ED.full_H = None
ED.build_full_H_from_bonds()
full_H_bond = ED.full_H # the one generated by NearstNeighborModel.calc_H_MPO_from_bond()
print("npc.norm(H0 - full_H_bond) = ", npc.norm(H0 - full_H_bond))
assert npc.norm(
H0 - full_H_bond) < 1.e-14 # round off errors on order of 1.e-15
def test_CouplingMPOModel_group():
m1 = MyMod(dict(x=0.5, L=5, bc_MPS='finite'))
model_params = {'L': 6, 'hz': np.random.random([6]), 'bc_MPS': 'finite'}
m2 = XXZChain(model_params)
for m in [m1, m2]:
print("model = ", m)
assert m.H_MPO.max_range == 1
# test grouping sites
ED = ExactDiag(m)
# ED.build_full_H_from_mpo()
ED.build_full_H_from_bonds()
m.group_sites(n=2)
assert m.H_MPO.max_range == 1
ED_gr = ExactDiag(m)
ED_gr.build_full_H_from_mpo()
H = ED.full_H.split_legs().to_ndarray()
Hgr = ED_gr.full_H.split_legs()
Hgr.idrop_labels()
Hgr = Hgr.split_legs().to_ndarray()
assert np.linalg.norm(H - Hgr) < 1.e-14
ED_gr.full_H = None
ED_gr.build_full_H_from_bonds()
Hgr = ED_gr.full_H.split_legs()
Hgr.idrop_labels()
Hgr = Hgr.split_legs().to_ndarray()
assert np.linalg.norm(H - Hgr) < 1.e-14
def test_ED():
# just quickly check that it runs without errors for a small system
xxz_pars = dict(L=4, Jxx=1., Jz=1., hz=0.0, bc_MPS='finite')
M = XXZChain(xxz_pars)
ED = ExactDiag(M)
ED.build_full_H_from_mpo()
H, ED.full_H = ED.full_H, None
ED.build_full_H_from_bonds()
H2 = ED.full_H
assert (npc.norm(H - H2, np.inf) < 1.e-14)
ED.full_diagonalization()
psi = ED.groundstate()
print("select charge_sector =", psi.qtotal)
ED2 = ExactDiag(M, psi.qtotal)
ED2.build_full_H_from_mpo()
ED2.full_diagonalization()
psi2 = ED2.groundstate()
full_psi2 = psi.zeros_like()
full_psi2[ED2._mask] = psi2
ov = npc.inner(psi, full_psi2, do_conj=True)
print("overlab <psi | psi2> = 1. -", 1. - ov)
assert (abs(abs(ov) - 1.) < 1.e-15)
# starting from a random guess in the correct charge sector,
# check if we can also do lanczos.
np.random.seed(12345)
psi3 = npc.Array.from_func(np.random.random,
psi2.legs,
qtotal=psi2.qtotal,
shape_kw='size')
E0, psi3, N = lanczos(ED2, psi3)
print("Lanczos E0 =", E0)
ov = npc.inner(psi3, psi2, do_conj=True)
print("overlab <psi2 | psi3> = 1. -", 1. - ov)
assert (abs(abs(ov) - 1.) < 1.e-15)
def test_CouplingMPOModel_group():
m = MyMod(dict(x=0.5, L=5, bc_MPS='finite'))
assert m.H_MPO.max_range == 1
# test grouping sites
ED = ExactDiag(m)
# ED.build_full_H_from_mpo()
ED.build_full_H_from_bonds()
m.group_sites(n=2)
assert m.H_MPO.max_range == 1
ED_gr = ExactDiag(m)
ED_gr.build_full_H_from_mpo()
H = ED.full_H.split_legs().to_ndarray()
Hgr = ED_gr.full_H.split_legs()
Hgr.idrop_labels()
Hgr = Hgr.split_legs().to_ndarray()
assert np.linalg.norm(H - Hgr) == 0
ED_gr.full_H = None
ED_gr.build_full_H_from_bonds()
Hgr = ED_gr.full_H.split_legs()
Hgr.idrop_labels()
Hgr = Hgr.split_legs().to_ndarray()
assert np.linalg.norm(H - Hgr) == 0
def test_CouplingMPOModel_group():
class MyMod(model.CouplingMPOModel, model.NearestNeighborModel):
def __init__(self, model_params):
model.CouplingMPOModel.__init__(self, model_params)
def init_sites(self, model_params):
return tenpy.networks.site.SpinHalfSite('parity')
def init_terms(self, model_params):
x = get_parameter(model_params, 'x', 1., self.name)
self.add_onsite_term(0.25, 0, 'Sz')
self.add_onsite_term(0.25, 4, 'Sz')
self.add_coupling_term(x, 0, 1, 'Sx', 'Sx')
self.add_coupling_term(2. * x, 1, 2, 'Sy', 'Sy')
self.add_coupling_term(3. * x, 3, 4, 'Sy', 'Sy')
m = MyMod(dict(x=0.5, L=5, bc_MPS='finite'))
m.test_sanity()
for Hb in m.H_bond:
if Hb is not None:
Hb.test_sanity()
# test grouping sites
ED = ExactDiag(m)
# ED.build_full_H_from_mpo()
ED.build_full_H_from_bonds()
m.group_sites(n=2)
ED_gr = ExactDiag(m)
ED_gr.build_full_H_from_mpo()
H = ED.full_H.split_legs().to_ndarray()
Hgr = ED_gr.full_H.split_legs()
Hgr.idrop_labels()
Hgr = Hgr.split_legs().to_ndarray()
assert np.linalg.norm(H - Hgr) == 0
ED_gr.full_H = None
ED_gr.build_full_H_from_bonds()
Hgr = ED_gr.full_H.split_legs()
Hgr.idrop_labels()
Hgr = Hgr.split_legs().to_ndarray()
assert np.linalg.norm(H - Hgr) == 0
def test_SpinChainNNN_comparison():
model_pars = {
'hz': 0.5,
'Jx': -2.,
'Jy': -2.,
'Jz': 0.4,
'L': 3,
'conserve': 'Sz',
'bc_MPS': 'finite'
}
M1 = spins_nnn.SpinChainNNN(model_pars.copy())
model_pars['L'] = 2 * model_pars['L']
M2 = spins_nnn.SpinChainNNN2(model_pars.copy())
M2.group_sites(2)
M2nn = NearestNeighborModel.from_MPOModel(M2)
ED1 = ExactDiag(M1)
ED2 = ExactDiag(M2)
ED2nn = ExactDiag(M2nn)
ED1.build_full_H_from_mpo()
ED2.build_full_H_from_mpo()
ED2nn.build_full_H_from_bonds()
assert (ED1.full_H - ED2.full_H).norm() < 1.e-13
assert (ED1.full_H - ED2nn.full_H).norm() < 1.e-13
