def mel(state1, state2):
term = 0
for sigma in [-1, 1]:
for i in range(N):
for j in range(N):
if (i != j and abs(i - j) == 1):
s2 = bg.clonestate(state2)
s2.move(i, j, sigma)
termtemp = bg.innerproduct(state1, s2)
term += termtemp
return term
def mel(state1, state2):
# calculate the hopping to right
term = 0
for sigma in [-1, 1]:
for i in range(N):
for j in range(N):
if (i != j and abs(i - j) == 1):
s2 = bg.clonestate(state2)
s2.move(i, j, sigma)
termtemp = bg.innerproduct(state1, s2)
# print(termtemp)
term += termtemp
return term