def two_body_old(sys, psi):
"""Contribution from two-body-terms commutator with c*_k c_k+1"""
# psi = np.reshape(psi,
# (fci.cistring.num_strings(sys.nsites, sys.nup), fci.cistring.num_strings(sys.nsites, sys.ndown)))
D = 0.
for i in range(sys.nsites):
w = (i + 1) % sys.nsites
v = (i - 1) % sys.nsites
D += harmonic.compute_inner_product(psi, sys.nsites,
(sys.nup, sys.ndown), [i, w, i, i],
[1, 0, 1, 0], [1, 1, 0, 0])
D += harmonic.compute_inner_product(psi, sys.nsites,
(sys.nup, sys.ndown), [i, i, i, w],
[1, 0, 1, 0], [1, 1, 0, 0])
D -= harmonic.compute_inner_product(psi, sys.nsites,
(sys.nup, sys.ndown), [v, i, i, i],
[1, 0, 1, 0], [1, 1, 0, 0])
D -= harmonic.compute_inner_product(psi, sys.nsites,
(sys.nup, sys.ndown), [i, i, v, i],
[1, 0, 1, 0], [1, 1, 0, 0])
return D.conj()
def one_energy(lat, psi, phi):
D = 0
for j in [0, 1]:
for i in range(lat.nsites - 1):
D += harmonic.compute_inner_product(psi, lat.nsites,
(lat.nup, lat.ndown),
[i, i + 1], [1, 0], [j, j])
# Assuming periodic conditions
D += harmonic.compute_inner_product(psi, lat.nsites,
(lat.nup, lat.ndown),
[lat.nsites - 1, 0], [1, 0],
[j, j])
one_e = -2 * lat.t * np.real(D.conj() * np.exp(-1j * phi))
return one_e
def nearest_neighbour(lat, psi):
psi = np.reshape(psi, (fci.cistring.num_strings(
lat.nsites, lat.nup), fci.cistring.num_strings(lat.nsites, lat.ndown)))
D = 0.
for j in [0, 1]:
for i in range(lat.nsites - 1):
D += harmonic.compute_inner_product(psi, lat.nsites,
(lat.nup, lat.ndown),
[i, i + 1], [1, 0], [j, j])
# Assuming periodic conditions
D += harmonic.compute_inner_product(psi, lat.nsites,
(lat.nup, lat.ndown),
[lat.nsites - 1, 0], [1, 0],
[j, j])
return D.conj()
def single_operator(lat, psi):
psi = np.reshape(psi, (fci.cistring.num_strings(lat.nsites, lat.nup), fci.cistring.num_strings(lat.nsites, lat.ndown)))
D = 0.
civec=psi
for j in [0, 1]:
for i in range(lat.nsites - 1):
D += harmonic.compute_inner_product(psi, lat.nsites, (lat.nup, lat.ndown), [i], [1], [j])
return D
def DHP(lat,psi):
# psi = np.reshape(psi,(fci.cistring.num_strings(lat.nsites,lat.nup),fci.cistring.num_strings(lat.nsites,lat.ndown)))
psi = np.reshape(psi,
(fci.cistring.num_strings(lat.nsites, lat.nup), fci.cistring.num_strings(lat.nsites, lat.ndown)))
D = 0.
for i in range(lat.nsites):
D += harmonic.compute_inner_product(psi,lat.nsites,(lat.nup,lat.ndown),[i,i,i,i],[1,0,1,0],[1,1,0,0])
# return D/lat.nsites
return D/lat.nsites
def two_energy(lat, psi):
two_e = 0
for i in range(lat.nsites):
two_e += harmonic.compute_inner_product(psi, lat.nsites,
(lat.nup, lat.ndown),
[i, i, i, i], [1, 0, 1, 0],
[1, 1, 0, 0])
# Assuming periodic conditions
return lat.U * two_e
def spin(lat,psi):
eta = 0.
for i in range(lat.nsites):
j = (i+1)%lat.nsites
#abba
eta += 0.5*harmonic.compute_inner_product(psi,lat.ne,(lat.nup,lat.ndown),[i,i,j,j],[1,0,1,0],[1,0,0,1])
#baab
eta += 0.5*harmonic.compute_inner_product(psi,lat.ne,(lat.nup,lat.ndown),[i,i,j,j],[1,0,1,0],[0,1,1,0])
#aaaa
eta += 0.25*harmonic.compute_inner_product(psi,lat.ne,(lat.nup,lat.ndown),[i,i,j,j],[1,0,1,0],[1,1,1,1])
#bbbb
eta += 0.25*harmonic.compute_inner_product(psi,lat.ne,(lat.nup,lat.ndown),[i,i,j,j],[1,0,1,0],[0,0,0,0])
#aabb
eta -= 0.25*harmonic.compute_inner_product(psi,lat.ne,(lat.nup,lat.ndown),[i,i,j,j],[1,0,1,0],[1,1,0,0])
#bbaa
eta -= 0.25*harmonic.compute_inner_product(psi,lat.ne,(lat.nup,lat.ndown),[i,i,j,j],[1,0,1,0],[0,0,1,1])
return eta.real/lat.nsites