def __init__(self,beta,L):
self.L = L
self.beta = beta
# Init exponential map
self.exp_table = dict()
for E in range(-4,5,2):
self.exp_table[E] = math.exp(2*beta*E)
# Init random spin configuration
self.spins = [ [2*self.randint(2)-1 for j in range(L)] for i in range(L) ]
# Init observables
self.energy = alpsalea.RealObservable('E')
self.magnetization = alpsalea.RealObservable('m')
self.abs_magnetization = alpsalea.RealObservable('|m|')
def __init__(self, beta, L, model=None):
# Init size and temp
self.L = L
self.beta = beta
# Init random spin configuration
self.spins = [[
spin.Spin(sx=0.0, sy=0.0, sz=2 * self.randint(2) - 1)
for j in range(L)
] for i in range(L)]
# Init observables
self.energy = alpsalea.RealObservable('E')
self.magnetization = alpsalea.RealObservable('m')
self.abs_magnetization = alpsalea.RealObservable('|m|')
self.magnetization_2 = alpsalea.RealObservable('m^2')
self.magnetization_4 = alpsalea.RealObservable('m^4')
self.accepted = 0
#==============================================================================
# HAMILTONIANS
#==============================================================================
def isingH(spin, i, j):
e = self.spins[(i-1+self.L)%self.L][j].sz +\
self.spins[(i+1)%self.L][j].sz +\
self.spins[i][(j-1+self.L)%self.L].sz +\
self.spins[i][(j+1)%self.L].sz
e *= -spin.sz
return e
def antiIsingH(spin, i, j):
e = self.spins[(i-1+self.L)%self.L][j].sz +\
self.spins[(i+1)%self.L][j].sz +\
self.spins[i][(j-1+self.L)%self.L].sz +\
self.spins[i][(j+1)%self.L].sz
e *= spin.sz
return e
# currently not long-range.
def dipoledipoleH(spin, i, j):
rCutOff = 3
e = 0
for dx in range(-1, 2, 2):
for dy in range(-1, 2, 2):
if (dx * dx + dy * dy >
rCutOff * rCutOff): #hard code for now.
r = math.sqrt(dx * dx + dy * dy)
rvec = spin.Spin(sx=dx, sy=dy, sz=0.0)
e += self.spins[i][j].dot(
self.spins[(i + dx) % self.L][(j + dy) % self.L])
e += (self.spins[i][j].dot(rvec)) * (self.spins[
(i + dx) % self.L][(j + dy) % self.L].dot(rvec))
e *= 1.0 / (r * r * r)
return e
#==============================================================================
# SPIN MOVE / FLIP TYPES
#==============================================================================
def flip180(spinToFlip):
return spin.Spin(sx=spinToFlip.sx,
sy=spinToFlip.sy,
sz=-spinToFlip.sz)
self.Potts6LookUp = [[0, 0, 1], [0, 0, -1], [0, 1, 0], [0, -1, 0],
[1, 0, 0], [-1, 0, 0]]
def flipPotts6(spinToFlip):
whichVector = self.randint(len(self.Potts6LookUp))
sx = self.Potts6LookUp[whichVector][0]
sy = self.Potts6LookUp[whichVector][1]
sz = self.Potts6LookUp[whichVector][2]
return spin.Spin(sx=sx, sy=sy, sz=sz)
if model == 'Ising':
self.energyLocal = isingH
self.flip = flip180
elif model == 'AntiFerroIsing':
self.energyLocal = antiIsingH
self.flip = flip180
elif model == 'dipole-dipole6':
self.energyLocal = dipoledipoleH
self.flip = flipPotts6