def test_MultiCouplingModel_explicit():
fermion_lat_cyl = lattice.Square(1,
2,
fermion_site,
bc='periodic',
bc_MPS='infinite')
M = model.MultiCouplingModel(fermion_lat_cyl)
# create a wired fermionic model with 3-body interactions
M.add_onsite(0.125, 0, 'N')
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, 1))
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, -1), 'JW')
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (1, 0), 'JW')
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (-1, 0), 'JW')
M.add_multi_coupling(4., 0, 'N', [(0, 'N', (2, 1))],
'Id') # a full unit cell inbetween!
# some wired mediated hopping along the diagonal
M.add_multi_coupling(1.125,
0,
'N',
other_ops=[(0, 'Cd', (0, 1)), (0, 'C', (1, 0))])
H_mpo = M.calc_H_MPO()
W0_new = H_mpo.get_W(0)
W1_new = H_mpo.get_W(1)
W2_new = H_mpo.get_W(2)
Id, JW, N = fermion_site.Id, fermion_site.JW, fermion_site.N
Cd, C = fermion_site.Cd, fermion_site.C
CdJW = Cd.matvec(JW)
JWC = JW.matvec(C)
NJW = N.matvec(JW)
# yapf: disable
W0_ex = [[Id, None, None, CdJW, None, JWC, N, None, None, None, N*0.125],
[None, None, Id, None, None, None, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, None, JW, None, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, None, Cd*1.5],
[None, Id, None, None, None, None, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, None, C*1.125],
[None, None, None, None, None, None, None, JW, None, None, None],
[None, None, None, None, None, None, None, None, JW, None, None],
[None, None, None, None, None, None, None, None, None, Id, None],
[None, None, None, None, None, None, None, None, None, None, Id]]
W1_ex = [[Id, None, None, None, None, None, None, None, CdJW, JWC, N, N*0.125],
[None, Id, None, None, None, None, None, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, JW, NJW, None, None, None, None, None, None, C*0.5],
[None, None, None, None, None, None, None, None, None, None, None, C*1.125],
[None, None, None, None, None, JW, None, None, None, None, None, Cd*0.5],
[None, None, None, None, None, None, Id, CdJW, None, None, None, None],
[None, None, None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, None, None, None, None, None, None, None, None, Cd*1.5],
[None, None, Id, None, None, None, None, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, None, None, Id]]
# yapf: enable
W0_ex = npc.grid_outer(W0_ex, W0_new.legs[:2])
W1_ex = npc.grid_outer(W1_ex, W1_new.legs[:2])
assert npc.norm(W0_new -
W0_ex) == 0. # coupling constants: no rounding errors
assert npc.norm(W1_new -
W1_ex) == 0. # coupling constants: no rounding errors
def test_CouplingModel_multi_couplings_explicit(use_plus_hc, JW):
fermion_lat_cyl = lattice.Square(1,
2,
fermion_site,
bc='periodic',
bc_MPS='infinite')
M = model.CouplingModel(fermion_lat_cyl)
# create a wired fermionic model with 3-body interactions
M.add_onsite(0.125, 0, 'N')
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, 1), plus_hc=use_plus_hc)
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (1, 0), JW, plus_hc=use_plus_hc)
if not use_plus_hc:
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, -1), JW)
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (-1, 0), JW)
# multi_coupling with a full unit cell inbetween the operators!
M.add_multi_coupling(4., [('N', (0, 0), 0), ('N', (-2, -1), 0)])
# some wired mediated hopping along the diagonal
M.add_multi_coupling(1.125, [('N', (0, 0), 0), ('Cd', (0, 1), 0),
('C', (1, 0), 0)])
H_mpo = M.calc_H_MPO()
W0_new = H_mpo.get_W(0)
W1_new = H_mpo.get_W(1)
Id, JW, N = fermion_site.Id, fermion_site.JW, fermion_site.N
Cd, C = fermion_site.Cd, fermion_site.C
CdJW = Cd.matvec(JW) # = Cd
CJW = C.matvec(JW) # = -C
NJW = N.matvec(JW)
# print(M.H_MPO_graph._build_grids())
# yapf: disable
W0_ex = [[Id, CJW, CdJW, None, N, None, None, None, None, None, N*0.125],
[None, None, None, None, None, None, None, None, None, None, Cd*-1.5],
[None, None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, JW, None, None, None, None, None, None, None],
[None, None, None, None, None, Id, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, None, C*1.125],
[None, None, None, None, None, None, Id, None, None, None, None],
[None, None, None, None, None, None, None, JW, None, None, None],
[None, None, None, None, None, None, None, None, JW, None, None],
[None, None, None, None, None, None, None, None, None, Id, None],
[None, None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, None, None, None, None, None, None, None, Id]]
W1_ex = [[Id, None, None, None, None, None, None, CJW, CdJW, N, None, N*0.125],
[None, JW, None, None, None, None, None, None, None, None, None, Cd*-0.5],
[None, None, JW, NJW, None, None, None, None, None, None, None, C*0.5],
[None, None, None, None, None, None, None, None, None, None, None, C*1.125],
[None, None, None, None, Id, CdJW, None, None, None, None, None, None],
[None, None, None, None, None, None, Id, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, None, None, None, None, None, None, None, None, Cd*-1.5],
[None, None, None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, None, None, None, None, None, None, None, Id, None],
[None, None, None, None, None, None, None, None, None, None, None, Id]]
# yapf: enable
W0_ex = npc.grid_outer(W0_ex, W0_new.legs[:2])
W1_ex = npc.grid_outer(W1_ex, W1_new.legs[:2])
assert npc.norm(W0_new -
W0_ex) == 0. # coupling constants: no rounding errors
assert npc.norm(W1_new -
W1_ex) == 0. # coupling constants: no rounding errors
def test_CouplingModel_explicit():
fermion_lat_cyl = lattice.Square(1,
2,
fermion_site,
bc='periodic',
bc_MPS='infinite')
M = model.CouplingModel(fermion_lat_cyl)
M.add_onsite(0.125, 0, 'N')
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, 1),
None) # auto-determine JW-string!
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, -1), None)
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (1, 0), None)
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (-1, 0), None)
M.add_coupling(4., 0, 'N', 0, 'N', (-2, -1),
None) # a full unit cell inbetween!
H_mpo = M.calc_H_MPO()
W0_new = H_mpo.get_W(0)
W1_new = H_mpo.get_W(1)
Id, JW, N = fermion_site.Id, fermion_site.JW, fermion_site.N
Cd, C = fermion_site.Cd, fermion_site.C
CdJW = Cd.matvec(JW) # = Cd
CJW = C.matvec(JW) # = -C
# yapf: disable
W0_ex = [[Id, CJW, CdJW, N, None, None, None, None, None, N*0.125],
[None, None, None, None, None, None, None, None, None, Cd*-1.5],
[None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, None, Id, None, None, None, None, None],
[None, None, None, None, None, Id, None, None, None, None],
[None, None, None, None, None, None, JW, None, None, None],
[None, None, None, None, None, None, None, JW, None, None],
[None, None, None, None, None, None, None, None, Id, None],
[None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, None, None, None, None, None, None, Id]]
W1_ex = [[Id, None, None, None, None, CJW, CdJW, N, None, N*0.125],
[None, JW, None, None, None, None, None, None, None, Cd*-0.5],
[None, None, JW, None, None, None, None, None, None, C*0.5],
[None, None, None, Id, None, None, None, None, None, None],
[None, None, None, None, Id, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, None, None, None, None, None, None, Cd*-1.5],
[None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, None, None, None, None, None, Id, None],
[None, None, None, None, None, None, None, None, None, Id]]
# yapf: enable
W0_ex = npc.grid_outer(W0_ex, W0_new.legs[:2])
W1_ex = npc.grid_outer(W1_ex, W1_new.legs[:2])
assert npc.norm(W0_new -
W0_ex) == 0. # coupling constants: no rounding errors
assert npc.norm(W1_new -
W1_ex) == 0. # coupling constants: no rounding errors
def test_CouplingModel_explicit():
fermion_lat_cyl = lattice.SquareLattice(1,
2,
fermion_site,
bc_MPS='infinite')
M = model.CouplingModel(fermion_lat_cyl, 'periodic')
M.add_onsite(0.125, 0, 'N')
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, 1), 'JW')
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, -1), 'JW')
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (1, 0), 'JW')
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (-1, 0), 'JW')
M.add_coupling(4., 0, 'N', 0, 'N', (2, 1),
'Id') # a full unit cell inbetween!
H_mpo = M.calc_H_MPO()
# MPO should be translation invariant!
W0_new = H_mpo.get_W(0)
W1_new = H_mpo.get_W(1)
Id, JW, N = fermion_site.Id, fermion_site.JW, fermion_site.N
Cd, C = fermion_site.Cd, fermion_site.C
CdJW = Cd.matvec(JW)
JWC = JW.matvec(C)
# yapf: disable
W0_ex = [[Id, None, None, CdJW, JWC, N, None, None, None, N*0.125],
[None, None, Id, None, None, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, None, None, None, None, None, None, Cd*1.5],
[None, Id, None, None, None, None, None, None, None, None],
[None, None, None, None, None, None, JW, None, None, None],
[None, None, None, None, None, None, None, JW, None, None],
[None, None, None, None, None, None, None, None, Id, None],
[None, None, None, None, None, None, None, None, None, Id]]
W1_ex = [[Id, None, None, None, None, None, CdJW, JWC, N, N*0.125],
[None, Id, None, None, None, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, JW, None, None, None, None, None, C*0.5],
[None, None, None, None, JW, None, None, None, None, Cd*0.5],
[None, None, None, None, None, Id, None, None, None, None],
[None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, None, None, None, None, None, None, Cd*1.5],
[None, None, Id, None, None, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, Id]]
# yapf: enable
W0_ex = npc.grid_outer(W0_ex, W0_new.legs[:2])
W1_ex = npc.grid_outer(W1_ex, W1_new.legs[:2])
assert npc.norm(W0_new -
W0_ex) == 0. # coupling constants: no rounding errors
assert npc.norm(W1_new -
W1_ex) == 0. # coupling constants: no rounding errors
def test_npc_grid_outer():
ci = chinfo3
p_leg = gen_random_legcharge(ci, 4)
legs_op = [p_leg, p_leg.conj()]
op_0 = 1.j * npc.Array.from_func(np.random.random, legs_op, qtotal=[0], shape_kw='size')
op_pl = npc.Array.from_func(np.random.random, legs_op, qtotal=[1], shape_kw='size')
op_min = npc.Array.from_func(np.random.random, legs_op, qtotal=[-1], shape_kw='size')
op_id = npc.eye_like(op_0)
grid = [[op_id, op_pl, op_min, op_0, None],
[None, None, None, None, op_min],
[None, None, None, None, op_pl],
[None, None, None, None, op_0],
[None, None, None, None, op_id]] # yapf: disable
leg_WL = npc.LegCharge.from_qflat(ci, ci.make_valid([[0], [1], [-1], [0], [0]]))
leg_WR = npc.LegCharge.from_qflat(ci, ci.make_valid([[0], [1], [-1], [0], [0]]), -1)
leg_WR_calc = npc.detect_grid_outer_legcharge(grid, [leg_WL, None], qconj=-1)[1]
leg_WR.test_equal(leg_WR_calc)
W = npc.grid_outer(grid, [leg_WL, leg_WR])
W.test_sanity()
Wflat = np.zeros([5, 5, 4, 4], dtype=W.dtype)
for idx, op in [[(0, 0), op_id], [(0, 1), op_pl], [(0, 2), op_min], [(0, 3), op_0],
[(1, 4), op_min], [(2, 4), op_pl], [(3, 4), op_0], [(4, 4), op_id]]:
Wflat[idx] = op.to_ndarray()
npt.assert_equal(W.to_ndarray(), Wflat)
def test_MPO():
s = spin_half
for bc in mpo.MPO._valid_bc:
for L in [4, 2, 1]:
print(bc, ", L =", L)
grid = [[s.Id, s.Sp, s.Sz], [None, None, s.Sm], [None, None, s.Id]]
legW = npc.LegCharge.from_qflat(s.leg.chinfo,
[[0], s.Sp.qtotal, [0]])
W = npc.grid_outer(grid, [legW, legW.conj()])
W.iset_leg_labels(['wL', 'wR', 'p', 'p*'])
Ws = [W] * L
if bc == 'finite':
Ws[0] = Ws[0][0:1, :, :, :]
Ws[-1] = Ws[-1][:, 2:3, :, :]
H = mpo.MPO([s] * L,
Ws,
bc=bc,
IdL=[0] * L + [None],
IdR=[None] + [-1] * (L))
H.test_sanity()
print(H.dim)
print(H.chi)
if L == 4:
H2 = H.group_sites(n=2)
H2.test_sanity()
assert H2.L == 2
def test_MPO():
s = spin_half
for bc in mpo.MPO._valid_bc:
for L in [4, 2, 1]:
print(bc, ", L =", L)
grid = [[s.Id, s.Sp, s.Sm, s.Sz], [None, None, None, s.Sm], [None, None, None, s.Sp],
[None, None, None, s.Id]]
legW = npc.LegCharge.from_qflat(s.leg.chinfo, [[0], s.Sp.qtotal, s.Sm.qtotal, [0]])
W = npc.grid_outer(grid, [legW, legW.conj()], grid_labels=['wL', 'wR'])
Ws = [W] * L
if bc == 'finite':
Ws[0] = Ws[0][0:1, :, :, :]
Ws[-1] = Ws[-1][:, 3:4, :, :]
H = mpo.MPO([s] * L, Ws, bc=bc, IdL=[0] * L + [None], IdR=[None] + [-1] * (L))
H_copy = mpo.MPO([s] * L, Ws, bc=bc, IdL=[0] * L + [None], IdR=[None] + [-1] * (L))
H.test_sanity()
print(H.dim)
print(H.chi)
assert H.is_equal(H) # everything should be equal to itself
assert H.is_hermitian()
H.sort_legcharges()
H.test_sanity()
assert H.is_equal(H_copy)
if L == 4:
H2 = H.group_sites(n=2)
H2.test_sanity()
assert H2.L == 2
def Ws(Aml, m):
"MPO for d_m^\dag (spin up)"
Cdu, Id = [site.get_op(op) for op in ('Cdu', 'Id')]
Wm = []
wL_leg = npc.LegCharge.from_qflat(chinfo, [op.qtotal for op in [Cdu, Id]],
qconj=+1) # set charge on the leg
for l in range(L):
Wml_grid = [[Id, None], [Aml[m, l] * Cdu, Id]]
Wml = npc.grid_outer(Wml_grid, [wL_leg, wL_leg.conj()],
grid_labels=['wL', 'wR']) # wL, wR, p, p*
Wm.append(Wml)
# Boundary case
Wm[0] = Wm[0][1:2, :] # second row
Wm[-1] = Wm[-1][:, 0:1] # first column
return Wm
psi = MPS.from_product_state(lat.mps_sites(), state, lat.bc_MPS)
print("2) create an MPO representing the AFM Heisenberg Hamiltonian")
# predefined physical spin-1/2 operators Sz, S+, S-
Sz, Sp, Sm, Id = site.Sz, site.Sp, site.Sm, site.Id
mpo_leg = npc.LegCharge.from_qflat(chinfo, [[0], [2], [-2], [0], [0]])
W_grid = [[Id, Sp, Sm, Sz, None ],
[None, None, None, None, 0.5 * Jxx * Sm],
[None, None, None, None, 0.5 * Jxx * Sp],
[None, None, None, None, Jz * Sz ],
[None, None, None, None, Id ]] # yapf:disable
W = npc.grid_outer(W_grid, [mpo_leg, mpo_leg.conj()])
W.iset_leg_labels(['wL', 'wR', 'p', 'p*']) # wL/wR = virtual left/right of the MPO
Ws = [W] * L
Ws[0] = W[:1, :]
Ws[-1] = W[:, -1:]
H = MPO(psi.sites, Ws, psi.bc, IdL=0, IdR=-1)
print("3) define 'environments' left and right")
# this is automatically done during initialization of MPOEnvironment
env = MPOEnvironment(psi, H, psi)
envL = env.get_LP(0)
envR = env.get_RP(L - 1)
print("4) contract MPS and MPO to calculate the energy <psi|H|psi>")
psi = MPS.from_product_state(lat.mps_sites(), state, lat.bc_MPS)
print("2) create an MPO representing the AFM Heisenberg Hamiltonian")
# predefined physical spin-1/2 operators Sz, S+, S-
Sz, Sp, Sm, Id = site.Sz, site.Sp, site.Sm, site.Id
mpo_leg = npc.LegCharge.from_qflat(chinfo, [[0], [2], [-2], [0], [0]])
W_grid = [[Id, Sp, Sm, Sz, None ],
[None, None, None, None, 0.5 * Jxx * Sm],
[None, None, None, None, 0.5 * Jxx * Sp],
[None, None, None, None, Jz * Sz ],
[None, None, None, None, Id ]] # yapf:disable
W = npc.grid_outer(W_grid, [mpo_leg, mpo_leg.conj()], grid_labels=['wL', 'wR'])
# wL/wR = virtual left/right of the MPO
Ws = [W] * L
Ws[0] = W[:1, :]
Ws[-1] = W[:, -1:]
H = MPO(psi.sites, Ws, psi.bc, IdL=0, IdR=-1)
print("3) define 'environments' left and right")
# this is automatically done during initialization of MPOEnvironment
env = MPOEnvironment(psi, H, psi)
envL = env.get_LP(0)
envR = env.get_RP(L - 1)
print("4) contract MPS and MPO to calculate the energy <psi|H|psi>")
def test_CouplingModel_multi_couplings_explicit(use_plus_hc, JW):
fermion_lat_cyl = lattice.Square(1,
2,
fermion_site,
bc='periodic',
bc_MPS='infinite')
M = model.CouplingModel(fermion_lat_cyl)
# create a weird fermionic model with 3-body interactions
M.add_onsite(0.125, 0, 'N')
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, 1), plus_hc=use_plus_hc)
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (1, 0), JW, plus_hc=use_plus_hc)
if not use_plus_hc:
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, -1), JW)
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (-1, 0), JW)
# multi_coupling with a full unit cell inbetween the operators!
M.add_multi_coupling(4., [('N', (0, 0), 0), ('N', (-2, -1), 0)])
# some weird mediated hopping along the diagonal
M.add_multi_coupling(1.125, [('N', (0, 0), 0), ('Cd', (0, 1), 0),
('C', (1, 0), 0)])
H_mpo = M.calc_H_MPO()
W0_new = H_mpo.get_W(0)
W1_new = H_mpo.get_W(1)
Id, JW, N = fermion_site.Id, fermion_site.JW, fermion_site.N
Cd, C = fermion_site.Cd, fermion_site.C
CdJW = Cd.matvec(JW) # = Cd
JWC = JW.matvec(C) # = C
NJW = N.matvec(JW)
# yapf: disable
H_MPO_graph = tenpy.networks.mpo.MPOGraph.from_terms((M.all_onsite_terms(),
M.all_coupling_terms(),
M.exp_decaying_terms),
M.lat.mps_sites(),
M.lat.bc_MPS)
H_MPO_graph._set_ordered_states()
from pprint import pprint
pprint(H_MPO_graph._ordered_states)
pprint(H_MPO_graph._build_grids())
print(M.all_coupling_terms().to_TermList())
# 0.50000 * Cd JW_0 C_1 +
# 1.50000 * Cd JW_0 C_2 +
# 0.50000 * JW C_0 Cd_1 +
# 1.50000 * JW C_0 Cd_2 +
# 1.50000 * Cd JW_1 C_3 +
# 1.50000 * JW C_1 Cd_3 +
# 4.00000 * N_0 N_5 +
# 4.00000 * N_1 N_4 +
# 1.12500 * N_0 Cd JW_1 C_2 +
# 1.12500 * Cd JW_0 N JW_1 C_3
W0_ex = [[Id, CdJW, JWC, N, None, None, None, None, None, N*0.125],
[None, None, None, None, None, Id, None, None, None, None],
[None, None, None, None, None, None, JW*1.5, None, None, None],
[None, None, None, None, None, None, None, JW*1.5, None, None],
[None, None, None, None, Id, None, None, None, None, None],
[None, None, None, None, None, None, JW*1.125, None, None, None],
[None, None, None, None, None, None, None, None, None, C],
[None, None, None, None, None, None, None, None, None, Cd],
[None, None, None, None, None, None, None, None, None, N],
[None, None, None, None, None, None, None, None, Id, None],
[None, None, None, None, None, None, None, None, None, Id]]
W1_ex = [[Id, None, CdJW, JWC, N, None, None, None, None, None, N*0.125],
[None, None, None, None, None, NJW, JW*1.5, None, None, None, C*0.5],
[None, None, None, None, None, None, None, JW*1.5, None, None, Cd*0.5],
[None, Id, None, None, None, None, CdJW*1.125, None, None, None, None],
[None, None, None, None, None, None, None, None, Id*4., None, None],
[None, None, None, None, None, None, None, None, None, Id*4., None],
[None, None, None, None, None, None, None, None, None, None, C],
[None, None, None, None, None, None, None, None, None, None, Cd],
[None, None, None, None, None, None, None, None, None, None, N],
[None, None, None, None, None, None, None, None, None, None, Id]]
# yapf: enable
W0_ex = npc.grid_outer(W0_ex, W0_new.legs[:2])
assert npc.norm(W0_new -
W0_ex) == 0. # coupling constants: no rounding errors
W1_ex = npc.grid_outer(W1_ex, W1_new.legs[:2])
assert npc.norm(W1_new -
W1_ex) == 0. # coupling constants: no rounding errors
def test_CouplingModel_explicit():
fermion_lat_cyl = lattice.Square(1,
2,
fermion_site,
bc='periodic',
bc_MPS='infinite')
M = model.CouplingModel(fermion_lat_cyl)
M.add_onsite(0.125, 0, 'N')
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, 1),
None) # auto-determine JW-string!
M.add_coupling(0.25, 0, 'Cd', 0, 'C', (0, -1), None)
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (1, 0), None)
M.add_coupling(1.5, 0, 'Cd', 0, 'C', (-1, 0), None)
M.add_coupling(4., 0, 'N', 0, 'N', (-2, -1),
None) # a full unit cell inbetween!
H_mpo = M.calc_H_MPO()
W0_new = H_mpo.get_W(0)
W1_new = H_mpo.get_W(1)
Id, JW, N = fermion_site.Id, fermion_site.JW, fermion_site.N
Cd, C = fermion_site.Cd, fermion_site.C
CdJW = Cd.matvec(JW) # = Cd
JWC = JW.matvec(C) # = C
# H_MPO_graph = tenpy.networks.mpo.MPOGraph.from_terms((M.all_onsite_terms(),
# M.all_coupling_terms(),
# M.exp_decaying_terms),
# M.lat.mps_sites(),
# M.lat.bc_MPS)
# H_MPO_graph._set_ordered_states()
# from pprint import pprint
# pprint(H_MPO_graph._ordered_states)
# print(M.all_coupling_terms().to_TermList())
# [{'IdL': 0,
# ('left', 0, 'Cd JW', 'JW'): 1,
# ('left', 0, 'JW C', 'JW'): 2,
# ('left', 0, 'N', 'Id'): 3,
# ('left', 1, 'Cd JW', 'JW'): 4,
# ('left', 1, 'JW C', 'JW'): 5,
# ('left', 1, 'N', 'Id'): 6,
# ('left', 0, 'N', 'Id', 2, 'Id', 'Id'): 7,
# ('left', 1, 'N', 'Id', 3, 'Id', 'Id'): 8},
# 'IdR': 9,
# {'IdL': 0,
# ('left', 0, 'Cd JW', 'JW'): 1,
# ('left', 0, 'JW C', 'JW'): 2,
# ('left', 0, 'N', 'Id'): 3,
# ('left', 1, 'Cd JW', 'JW'): 4,
# ('left', 1, 'JW C', 'JW'): 5,
# ('left', 1, 'N', 'Id'): 6},
# ('left', 0, 'N', 'Id', 2, 'Id', 'Id'): 7,
# ('left', 0, 'N', 'Id', 2, 'Id', 'Id', 4, 'Id', 'Id'): 8,
# 'IdR': 9,
# 0.50000 * Cd JW_0 C_1 +
# 1.50000 * Cd JW_0 C_2 +
# 0.50000 * JW C_0 Cd_1 +
# 1.50000 * JW C_0 Cd_2 +
# 4.00000 * N_0 N_5 +
# 1.50000 * Cd JW_1 C_3 +
# 1.50000 * JW C_1 Cd_3 +
# 4.00000 * N_1 N_4
# yapf: disable
W0_ex = [[Id, CdJW, JWC, N, None, None, None, None, None, N*0.125],
[None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, None, None, None, None, None, None, Cd*1.5],
[None, None, None, None, None, None, None, Id, None, None],
[None, None, None, None, JW, None, None, None, None, None],
[None, None, None, None, None, JW, None, None, None, None],
[None, None, None, None, None, None, Id, None, None, None],
[None, None, None, None, None, None, None, None, Id, None],
[None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, None, None, None, None, None, None, Id]]
W1_ex = [[Id, None, None, None, CdJW, JWC, N, None, None, N*0.125],
[None, JW, None, None, None, None, None, None, None, C*0.5],
[None, None, JW, None, None, None, None, None, None, Cd*0.5],
[None, None, None, Id, None, None, None, None, None, None],
[None, None, None, None, None, None, None, None, None, C*1.5],
[None, None, None, None, None, None, None, None, None, Cd*1.5],
[None, None, None, None, None, None, None, None, Id, None],
[None, None, None, None, None, None, None, Id, None, None],
[None, None, None, None, None, None, None, None, None, N*4.0],
[None, None, None, None, None, None, None, None, None, Id]]
# yapf: enable
W0_ex = npc.grid_outer(W0_ex, W0_new.legs[:2])
W1_ex = npc.grid_outer(W1_ex, W1_new.legs[:2])
assert npc.norm(W0_new -
W0_ex)**2 == 0. # coupling constants: no rounding errors
assert npc.norm(W1_new -
W1_ex)**2 == 0. # coupling constants: no rounding errors
