def test_apply(self):
psi_abc = MPS_rand_state(20, bond_dim=7)
X = PTPTLazyMPS(psi_abc, sysa=range(5, 10), sysb=range(12, 16))
v0 = EEMPS_rand_state(X.sysa, X.sysb, nsites=X.TN.nsites, bond_dim=7)
vf = X.apply(v0)
assert vf.site_ind_id == 'k{}'
assert vf.site_tag_id == 'I{}'
v0d, Xd, vfd = map(lambda x: x.to_dense(), (v0, X, vf))
assert_allclose(vfd, Xd @ v0d)
def test_realistic(self):
ham = MPO_ham_heis(20)
dmrg = DMRG2(ham, bond_dims=[4, 8])
dmrg.solve()
sysa, sysb = range(3, 9), range(12, 17)
rho_ab_pt = PTPTLazyMPS(dmrg.state, sysa, sysb)
xf = approx_spectral_function(rho_ab_pt, lambda x: x, beta_tol=1e-6,
tol=0.05, verbosity=2, max_bond=20)
assert_allclose(1, xf, rtol=0.5, atol=0.1)
def test_init(self, sysa, sysb):
p = MPS_rand_state(12, 7)
pX = PTPTLazyMPS(p, sysa=sysa, sysb=sysb)
assert len(pX.TN.tensors) == (2 * len(sysa) + 2 * len(sysb) +
int(max(sysa) + 1 != min(sysb)))
pt = pX.TN.reindex({
pX.upper_ind_id.format(i): pX.lower_ind_id.format(i)
for i in (*pX.sysa, *pX.sysb)
})
assert_allclose(pt.contract_tags(...), 1.0)
def test_realistic_ent(self):
n = 12
sysa, sysb = range(3, 6), range(6, 8)
ham = MPO_ham_heis(n)
dmrg = DMRG2(ham, bond_dims=[2, 4])
dmrg.solve()
rho_ab_pt = PTPTLazyMPS(dmrg.state, sysa, sysb)
psi0 = dmrg.state.to_dense()
lne = logneg_subsys(psi0, [2] * n, sysa=sysa, sysb=sysb)
lnx = log2(
approx_spectral_function(rho_ab_pt, abs, tol=0.1, verbosity=2))
assert_allclose(lne, lnx, rtol=0.5, atol=0.1)
def test_construct_tridiag_works(self, sysa, sysb):
p = MPS_rand_state(12, 7)
pX = PTPTLazyMPS(p, sysa=sysa, sysb=sysb)
for _ in construct_lanczos_tridiag_PTPTLazyMPS(pX, 5):
pass