def CoulombFactory(site0,
site1,
*,
spin0=0,
spin1=0,
orbit0=0,
orbit1=0,
coeff=1.0):
"""
Generate Coulomb interaction term: '$U n_i n_j$'.
These parameters suffixed with '0' are for the 1st operator and '1' for
2nd operator.
Parameters
----------
site0, site1 : list, tuple or 1D np.ndarray
The coordinates of the localized single-particle state.
`site0` and `site1` should be 1D array with length 1, 2 or 3.
spin0, spin1 : int, optional, keyword-only
The spin index of the single-particle state.
Default: 0.
orbit0, orbit1 : int, optional, keyword-only
The orbit index of the single-particle state.
Default: 0.
coeff : int or float, optional, keyword-only
The coefficient of this term.
Default: 1.0.
Returns
-------
term : ParticleTerm
The corresponding Coulomb interaction term.
Examples
--------
>>> from HamiltonianPy.quantumoperator import CoulombFactory
>>> term = CoulombFactory((0, 0), (1, 1), spin0=0, spin1=1)
>>> print(term)
The coefficient of this term: 1.0
The component operators:
AoC(otype=CREATION, site=(0, 0), spin=0, orbit=0)
AoC(otype=ANNIHILATION, site=(0, 0), spin=0, orbit=0)
AoC(otype=CREATION, site=(1, 1), spin=1, orbit=0)
AoC(otype=ANNIHILATION, site=(1, 1), spin=1, orbit=0)
"""
c0 = AoC(CREATION, site=site0, spin=spin0, orbit=orbit0)
a0 = AoC(ANNIHILATION, site=site0, spin=spin0, orbit=orbit0)
c1 = AoC(CREATION, site=site1, spin=spin1, orbit=orbit1)
a1 = AoC(ANNIHILATION, site=site1, spin=spin1, orbit=orbit1)
return ParticleTerm((c0, a0, c1, a1),
coeff=coeff,
classification="Coulomb")
def test_MultiKrylov():
import logging
import sys
logging.basicConfig(stream=sys.stdout, level=logging.INFO)
site_num = 12
sites = np.arange(site_num).reshape((-1, 1))
state_indices_table = IndexTable(StateID(site=site) for site in sites)
bases = np.arange(1 << site_num, dtype=np.uint64)
HM = 0.0
for i in range(site_num):
C = AoC(CREATION, site=sites[i])
A = AoC(ANNIHILATION, site=sites[(i + 1) % site_num])
HM += ParticleTerm([C, A]).matrix_repr(state_indices_table, bases)
HM += HM.getH()
(GE, ), GS = eigsh(HM, k=1, which="SA")
excited_states = {}
i, j = np.random.randint(0, site_num, 2)
keys = ["Ci", "Cj", "Ai", "Aj"]
otypes = [CREATION, CREATION, ANNIHILATION, ANNIHILATION]
indices = [i, j, i, j]
for key, otype, index in zip(keys, otypes, indices):
excited_states[key] = AoC(otype, site=sites[i]).matrix_repr(
state_indices_table, bases
).dot(GS)
krylovs_matrix, krylovs_vectors = lanczos.MultiKrylov(HM, excited_states)
omega = np.random.random() + 0.01j
pairs = [("Ci", "Cj"), ("Ai", "Aj")]
for coeff, (key0, key1) in zip([-1, 1], pairs):
HMProjected = krylovs_matrix[key1]
krylov_space_dim = HMProjected.shape[0]
I = np.identity(krylov_space_dim)
bra = krylovs_vectors[key1][key0]
ket = krylovs_vectors[key1][key1]
gf = np.vdot(
bra, np.linalg.solve(
(omega + coeff * GE) * I + coeff * HMProjected, ket
)
)
I = np.identity(len(bases))
gf_ref = np.vdot(
excited_states[key0],
np.linalg.solve(
(omega + coeff * GE) * I + coeff * HM.toarray(),
excited_states[key1]
)
)
assert np.allclose(gf, gf_ref)
def HubbardFactory(site, *, orbit=0, coeff=1.0):
"""
Generate Hubbard term: '$U n_{i\\uparrow} n_{i\\downarrow}$'.
This function is valid only for spin-1/2 system.
Parameters
----------
site : list, tuple or 1D np.ndarray
The coordinates of the localized single-particle state.
`site` should be 1D array with length 1,2 or 3.
orbit : int, optional, keyword-only
The orbit index of the single-particle state.
Default: 0.
coeff : int or float, optional, keyword-only
The coefficient of this term.
Default: 1.0.
Returns
-------
term : ParticleTerm
The corresponding Hubbard term.
Examples
--------
>>> from HamiltonianPy.quantumoperator import HubbardFactory
>>> term = HubbardFactory(site=(0, 0))
>>> print(term)
The coefficient of this term: 1.0
The component operators:
AoC(otype=CREATION, site=(0, 0), spin=1, orbit=0)
AoC(otype=ANNIHILATION, site=(0, 0), spin=1, orbit=0)
AoC(otype=CREATION, site=(0, 0), spin=0, orbit=0)
AoC(otype=ANNIHILATION, site=(0, 0), spin=0, orbit=0)
"""
c_up = AoC(CREATION, site=site, spin=SPIN_UP, orbit=orbit)
c_down = AoC(CREATION, site=site, spin=SPIN_DOWN, orbit=orbit)
a_up = AoC(ANNIHILATION, site=site, spin=SPIN_UP, orbit=orbit)
a_down = AoC(ANNIHILATION, site=site, spin=SPIN_DOWN, orbit=orbit)
return ParticleTerm((c_up, a_up, c_down, a_down),
coeff=coeff,
classification="Coulomb")
def Schwinger(self):
"""
Return the Schwinger Fermion representation of this spin operator.
"""
coordinate = self.coordinate
C_UP = AoC(otype=CREATION, site=coordinate, spin=SPIN_UP)
C_DOWN = AoC(otype=CREATION, site=coordinate, spin=SPIN_DOWN)
A_UP = AoC(otype=ANNIHILATION, site=coordinate, spin=SPIN_UP)
A_DOWN = AoC(otype=ANNIHILATION, site=coordinate, spin=SPIN_DOWN)
terms = []
SMatrix = self.matrix()
for row_index, row_aoc in enumerate((C_UP, C_DOWN)):
for col_index, col_aoc in enumerate((A_UP, A_DOWN)):
coeff = SMatrix[row_index, col_index]
if coeff != 0.0:
terms.append(ParticleTerm([row_aoc, col_aoc], coeff=coeff))
return terms
def CPFactory(site, *, spin=0, orbit=0, coeff=1.0):
"""
Generate chemical potential term: '$\\mu c_i^{\\dagger} c_i$'.
Parameters
----------
site : list, tuple or 1D np.ndarray
The coordinates of the localized single-particle state.
The `site` parameter should be 1D array with length 1,2 or 3.
spin : int, optional, keyword-only
The spin index of the single-particle state.
Default: 0.
orbit : int, optional, keyword-only
The orbit index of the single-particle state.
Default: 0.
coeff : int or float, optional, keyword-only
The coefficient of this term.
Default: 1.0.
Returns
-------
term : ParticleTerm
The corresponding chemical potential term.
Examples
--------
>>> from HamiltonianPy.quantumoperator import CPFactory
>>> term = CPFactory((0, 0))
>>> print(term)
The coefficient of this term: 1.0
The component operators:
AoC(otype=CREATION, site=(0, 0), spin=0, orbit=0)
AoC(otype=ANNIHILATION, site=(0, 0), spin=0, orbit=0)
"""
c = AoC(CREATION, site=site, spin=spin, orbit=orbit)
a = AoC(ANNIHILATION, site=site, spin=spin, orbit=orbit)
return ParticleTerm((c, a), coeff=coeff, classification="number")
def PairingFactory(site0,
site1,
*,
spin0=0,
spin1=0,
orbit0=0,
orbit1=0,
coeff=1.0,
which="h"):
"""
Generate pairing term: '$p c_i^{\\dagger} c_j^{\\dagger}$' or '$p c_i c_j$'.
These parameters suffixed with '0' are for the 1st operator and '1' for
2nd operator.
Parameters
----------
site0, site1 : list, tuple or 1D np.ndarray
The coordinates of the localized single-particle state.
`site0` and `site1` should be 1D array with length 1, 2 or 3.
spin0, spin1 : int, optional, keyword-only
The spin index of the single-particle state.
Default: 0.
orbit0, orbit1 : int, optional, keyword-only
The orbit index of the single-particle state.
Default: 0.
coeff : int, float or complex, optional, keyword-only
The coefficient of this term.
Default: 1.0.
which : str, optional, keyword-only
Determine whether to generate a particle- or hole-pairing term.
Valid values:
["h" | "hole"] for hole-pairing;
["p" | "particle"] for particle-pairing.
Default: "h".
Returns
-------
term : ParticleTerm
The corresponding pairing term.
Examples
--------
>>> from HamiltonianPy.quantumoperator import PairingFactory
>>> term = PairingFactory((0, 0), (1, 1), spin0=0, spin1=1, which="h")
>>> print(term)
The coefficient of this term: 1.0
The component operators:
AoC(otype=ANNIHILATION, site=(0, 0), spin=0, orbit=0)
AoC(otype=ANNIHILATION, site=(1, 1), spin=1, orbit=0)
>>> term = PairingFactory((0, 0), (1, 1), spin0=0, spin1=1, which="p")
>>> print(term)
The coefficient of this term: 1.0
The component operators:
AoC(otype=CREATION, site=(0, 0), spin=0, orbit=0)
AoC(otype=CREATION, site=(1, 1), spin=1, orbit=0)
"""
assert which in ("h", "hole", "p", "particle")
otype = ANNIHILATION if which in ("h", "hole") else CREATION
aoc0 = AoC(otype, site=site0, spin=spin0, orbit=orbit0)
aoc1 = AoC(otype, site=site1, spin=spin1, orbit=orbit1)
return ParticleTerm((aoc0, aoc1), coeff=coeff)
def HoppingFactory(site0,
site1,
*,
spin0=0,
spin1=None,
orbit0=0,
orbit1=None,
coeff=1.0):
"""
Generate hopping term: '$t c_i^{\\dagger} c_j$'.
These parameters suffixed with '0' are for the creation operator and '1'
for annihilation operator.
Parameters
----------
site0, site1 : list, tuple or 1D np.ndarray
The coordinates of the localized single-particle state.
`site0` and `site1` should be 1D array with length 1, 2 or 3.
spin0, spin1 : int, optional, keyword-only
The spin index of the single-particle state.
The default value for `spin0` is 0;
The default value for `spin1` is None, which implies that `spin1`
takes the same value as `spin0`.
orbit0, orbit1 : int, optional, keyword-only
The orbit index of the single-particle state.
The default value for `orbit0` is 0;
The default value for `orbit1` is None, which implies that `orbit1`
takes the same value as `orbit0`.
coeff : int, float or complex, optional, keyword-only
The coefficient of this term.
Default: 1.0.
Returns
-------
term : ParticleTerm
The corresponding hopping term.
Examples
--------
>>> from HamiltonianPy.quantumoperator import HoppingFactory
>>> term = HoppingFactory(site0=(0, 0), site1=(1, 1), spin0=1)
>>> print(term)
The coefficient of this term: 1.0
The component operators:
AoC(otype=CREATION, site=(0, 0), spin=1, orbit=0)
AoC(otype=ANNIHILATION, site=(1, 1), spin=1, orbit=0)
>>> term = HoppingFactory(site0=(0, 0), site1=(1, 1), spin0=0, spin1=1)
>>> print(term)
The coefficient of this term: 1.0
The component operators:
AoC(otype=CREATION, site=(0, 0), spin=0, orbit=0)
AoC(otype=ANNIHILATION, site=(1, 1), spin=1, orbit=0)
"""
if spin1 is None:
spin1 = spin0
if orbit1 is None:
orbit1 = orbit0
c = AoC(CREATION, site=site0, spin=spin0, orbit=orbit0)
a = AoC(ANNIHILATION, site=site1, spin=spin1, orbit=orbit1)
classification = "hopping" if c.state != a.state else "number"
return ParticleTerm((c, a), coeff=coeff, classification=classification)