def __init__(self,
comm,
system,
beta,
dt,
options={},
H1=None,
verbose=False):
OneBody.__init__(self,
comm,
system,
beta,
dt,
options,
H1=H1,
verbose=verbose)
self.alpha = options.get('alpha', 0.75)
self.max_scf_it = options.get('max_scf_it', self.max_it)
self.max_macro_it = options.get('max_macro_it', self.max_it)
self.find_mu = options.get('find_mu', True)
if comm.rank == 0:
P, HMF, mu = self.thermal_hartree_fock(system, beta)
muN = mu * numpy.eye(system.nbasis, dtype=self.G.dtype)
dmat = numpy.array([
scipy.linalg.expm(-dt * (HMF[0] - muN)),
scipy.linalg.expm(-dt * (HMF[1] - muN))
])
dmat_inv = numpy.array([
scipy.linalg.inv(self.dmat[0], check_finite=False),
scipy.linalg.inv(self.dmat[1], check_finite=False)
])
G = numpy.array(
[greens_function(self.dmat[0]),
greens_function(self.dmat[1])])
data = {
'P': P,
'mu': mu,
'dmat': dmat,
'dmat_inv': dmat_inv,
'G': G
}
else:
data = None
data = comm.bcast(data, root=0)
self.P = data['P']
self.nav = particle_number(self.P).real
self.dmat = data['dmat']
self.dmat_inv = data['dmat_inv']
self.G = data['G']
self.mu = data['mu']
def scf(self, system, beta, mu, P):
# 1. Compute HMF
HMF = fock_matrix(system, P)
dt = self.dtau
muN = mu * numpy.eye(system.nbasis, dtype=self.G.dtype)
rho = numpy.array([
scipy.linalg.expm(-dt * (HMF[0] - muN)),
scipy.linalg.expm(-dt * (HMF[1] - muN))
])
Pold = one_rdm_stable(rho, self.num_bins)
if self.verbose:
print(" # Running Thermal SCF.")
for it in range(self.max_scf_it):
HMF = fock_matrix(system, Pold)
rho = numpy.array([
scipy.linalg.expm(-dt * (HMF[0] - muN)),
scipy.linalg.expm(-dt * (HMF[1] - muN))
])
Pnew = (1 - self.alpha) * one_rdm_stable(
rho, self.num_bins) + self.alpha * Pold
change = numpy.linalg.norm(Pnew - Pold)
if change < self.deps:
break
if self.verbose:
N = particle_number(P).real
E = local_energy(system, P, opt=False)[0].real
S = entropy(beta, mu, HMF)
omega = E - mu * N - 1.0 / beta * S
print(
" # Iteration: {:4d} dP: {:13.8e} Omega: {:13.8e}".format(
it, change, omega.real))
Pold = Pnew.copy()
if self.verbose:
N = particle_number(P).real
print(" # Average particle number: {:13.8e}".format(N))
return HMF
def __init__(self,
comm,
system,
beta,
dt,
options={},
nav=None,
H1=None,
verbose=False):
self.name = 'thermal'
self.verbose = verbose
if H1 is None:
try:
self.H1 = system.H1
except AttributeError:
self.H1 = system.h1e
else:
self.H1 = H1
if verbose:
print("# beta in OneBody: {}".format(beta))
print("# dt in OneBody: {}".format(dt))
dmat_up = scipy.linalg.expm(-dt * (self.H1[0]))
dmat_down = scipy.linalg.expm(-dt * (self.H1[1]))
self.dmat = numpy.array([dmat_up, dmat_down])
cond = numpy.linalg.cond(self.dmat[0])
if verbose:
print("# condition number of BT: {: 10e}".format(cond))
if nav is not None:
self.nav = nav
else:
self.nav = options.get("nav", None)
if self.nav is None:
self.nav = system.nup + system.ndown
if verbose:
print("# Target average electron number: {}".format(self.nav))
self.max_it = options.get('max_it', 1000)
self.deps = options.get('threshold', 1e-6)
self.mu = options.get('mu', None)
self.num_slices = int(beta / dt)
self.stack_size = options.get("stack_size", None)
if (self.stack_size == None):
if verbose:
print("# Estimating stack size from BT.")
eigs, ev = scipy.linalg.eigh(self.dmat[0])
emax = numpy.max(eigs)
emin = numpy.min(eigs)
self.cond = numpy.linalg.cond(self.dmat[0])
# We will end up multiplying many BTs together. Can roughly determine
# safe stack size from condition number of BT as the condition number of
# the product will scale roughly as cond(BT)^(number of products).
# We can determine a conservative stack size by requiring that the
# condition number of the product does not exceed 1e3.
self.stack_size = min(self.num_slices,
int(3.0 / numpy.log10(self.cond)))
if verbose:
print("# Initial stack size, # of slices: {}, {}".format(
self.stack_size, self.num_slices))
# adjust stack size
self.stack_size = update_stack(self.stack_size,
self.num_slices,
verbose=verbose)
self.num_bins = int(beta / (self.stack_size * dt))
if verbose:
print("# Number of stacks: {}".format(self.num_bins))
sign = 1
if system._alt_convention:
if verbose:
print(
"# Using alternate sign convention for chemical potential."
)
sign = -1
dtau = self.stack_size * dt
self.dtau = dtau
if self.mu is None:
self.rho = numpy.array([
scipy.linalg.expm(-dtau * (self.H1[0])),
scipy.linalg.expm(-dtau * (self.H1[1]))
])
if comm.rank == 0:
mu = find_chemical_potential(system,
self.rho,
dtau,
self.num_bins,
self.nav,
deps=self.deps,
max_it=self.max_it,
verbose=verbose)
else:
mu = None
self.mu = comm.bcast(mu, root=0)
else:
self.rho = numpy.array([
scipy.linalg.expm(-dtau * (self.H1[0])),
scipy.linalg.expm(-dtau * (self.H1[1]))
])
if verbose:
print("# Chemical potential in trial density matrix: {: .10e}".
format(self.mu))
if system.mu is None:
system.mu = self.mu
self.P = one_rdm_stable(
compute_rho(self.rho, self.mu, dtau, sign=sign), self.num_bins)
self.nav = particle_number(self.P).real
if verbose:
print("# Average particle number in trial density matrix: "
"{}".format(self.nav))
self.dmat = compute_rho(self.dmat, self.mu, dt, sign=sign)
self.dmat_inv = numpy.array([
scipy.linalg.inv(self.dmat[0], check_finite=False),
scipy.linalg.inv(self.dmat[1], check_finite=False)
])
self.G = numpy.array(
[greens_function(self.dmat[0]),
greens_function(self.dmat[1])])
self.error = False
def update(self, system, qmc, trial, psi, step, free_projection=False):
"""Update mixed estimates for walkers.
Parameters
----------
system : system object.
Container for model input options.
qmc : :class:`pauxy.state.QMCOpts` object.
Container for qmc input options.
trial : :class:`pauxy.trial_wavefunction.X' object
Trial wavefunction class.
psi : :class:`pauxy.walkers.Walkers` object
CPMC wavefunction.
step : int
Current simulation step
free_projection : bool
True if doing free projection.
"""
if free_projection:
for i, w in enumerate(psi.walkers):
# For T > 0 w.ot = 1 always.
wfac = w.weight * w.ot * w.phase
if step % self.energy_eval_freq == 0:
w.greens_function(trial)
if self.eval_energy:
E, T, V = w.local_energy(system)
else:
E, T, V = 0, 0, 0
self.estimates[self.names.enumer] += wfac * E
self.estimates[self.names.e1b:self.names.e2b +
1] += (wfac * numpy.array([T, V]))
self.estimates[self.names.edenom] += wfac
if self.thermal:
nav = particle_number(one_rdm_from_G(w.G))
self.estimates[self.names.nav] += wfac * nav
self.estimates[self.names.uweight] += w.unscaled_weight
self.estimates[self.names.uweight] += w.weight
self.estimates[self.names.ehyb] += wfac * w.hybrid_energy
self.estimates[self.names.ovlp] += wfac * abs(w.ot)
else:
# When using importance sampling we only need to know the current
# walkers weight as well as the local energy, the walker's overlap
# with the trial wavefunction is not needed.
for i, w in enumerate(psi.walkers):
if self.thermal:
if self.average_gf:
E_sum = 0
T_sum = 0
V_sum = 0
nav = 0
for ts in range(w.stack_length):
w.greens_function(trial,
slice_ix=ts * w.stack_size)
E, T, V = w.local_energy(system,
two_rdm=self.two_rdm)
E_sum += E
T_sum += T
V_sum += V
nav += particle_number(one_rdm_from_G(w.G))
self.estimates[
self.names.nav] += w.weight * nav / w.stack_length
self.estimates[
self.names.
enumer] += w.weight * E_sum.real / w.stack_length
self.estimates[self.names.e1b:self.names.e2b + 1] += (
w.weight * numpy.array([T_sum, V_sum]).real /
w.stack_length)
else:
w.greens_function(trial)
E, T, V = w.local_energy(system, two_rdm=self.two_rdm)
nav = particle_number(one_rdm_from_G(w.G))
self.estimates[self.names.nav] += w.weight * nav
self.estimates[self.names.enumer] += w.weight * E.real
self.estimates[self.names.e1b:self.names.e2b +
1] += (w.weight *
numpy.array([T, V]).real)
self.estimates[self.names.edenom] += w.weight
else:
if step % self.energy_eval_freq == 0:
w.greens_function(trial)
if self.eval_energy:
E, T, V = w.local_energy(system)
else:
E, T, V = 0, 0, 0
self.estimates[self.names.enumer] += w.weight * E.real
self.estimates[self.names.e1b:self.names.e2b +
1] += (w.weight *
numpy.array([T, V]).real)
self.estimates[self.names.edenom] += w.weight
self.estimates[self.names.uweight] += w.unscaled_weight
self.estimates[self.names.weight] += w.weight
self.estimates[self.names.ovlp] += w.weight * abs(w.ot)
self.estimates[self.names.ehyb] += w.weight * w.hybrid_energy
if self.calc_one_rdm:
start = self.names.time + 1
end = self.names.time + 1 + w.G.size
self.estimates[start:end] += w.weight * w.G.flatten().real
if self.calc_two_rdm is not None:
start = end
end = end + self.two_rdm.size
self.estimates[
start:end] += w.weight * self.two_rdm.flatten().real
def __init__(self, walker_opts, system, trial, verbose=False):
self.weight = walker_opts.get('weight', 1.0)
self.unscaled_weight = self.weight
self.phase = 1.0 + 0.0j
self.alive = True
self.num_slices = trial.num_slices
dtype = numpy.complex128
self.G = numpy.zeros(trial.dmat.shape, dtype=dtype)
self.nbasis = trial.dmat[0].shape[0]
self.total_weight = 0
self.stack_size = walker_opts.get('stack_size', None)
max_diff_diag = numpy.linalg.norm(
(numpy.diag(trial.dmat[0].diagonal()) - trial.dmat[0]))
if max_diff_diag < 1e-10:
self.diagonal_trial = True
if verbose:
print("# Trial density matrix is diagonal.")
else:
self.diagonal_trial = False
if verbose:
print("# Trial density matrix is not diagonal.")
if self.stack_size == None:
self.stack_size = trial.stack_size
if (self.num_slices //
self.stack_size) * self.stack_size != self.num_slices:
if verbose:
print("# Input stack size does not divide number of slices.")
self.stack_size = update_stack(self.stack_size, self.num_slices,
verbose)
if self.stack_size > trial.stack_size:
if verbose:
print("# Walker stack size differs from that estimated from "
"trial density matrix.")
print("# Be careful. cond(BT)**stack_size: %10.3e." %
(trial.cond**self.stack_size))
self.stack_length = self.num_slices // self.stack_size
if verbose:
print("# Walker stack size: {}".format(self.stack_size))
self.lowrank = walker_opts.get('low_rank', False)
self.lowrank_thresh = walker_opts.get('low_rank_thresh', 1e-6)
if verbose:
print("# Using low rank trick: {}".format(self.lowrank))
self.stack = PropagatorStack(self.stack_size,
trial.num_slices,
trial.dmat.shape[-1],
dtype,
trial.dmat,
trial.dmat_inv,
diagonal=self.diagonal_trial,
lowrank=self.lowrank,
thresh=self.lowrank_thresh)
# Initialise all propagators to the trial density matrix.
self.stack.set_all(trial.dmat)
self.greens_function_qr_strat(trial)
self.stack.G = self.G
self.M0 = numpy.array([
scipy.linalg.det(self.G[0], check_finite=False),
scipy.linalg.det(self.G[1], check_finite=False)
])
self.stack.ovlp = numpy.array([1.0 / self.M0[0], 1.0 / self.M0[1]])
self.ot = 1.0
# # temporary storage for stacks...
I = numpy.identity(system.nbasis, dtype=dtype)
One = numpy.ones(system.nbasis, dtype=dtype)
self.Tl = numpy.array([I, I])
self.Ql = numpy.array([I, I])
self.Dl = numpy.array([One, One])
self.Tr = numpy.array([I, I])
self.Qr = numpy.array([I, I])
self.Dr = numpy.array([One, One])
self.hybrid_energy = 0.0
if verbose:
eloc = self.local_energy(system)
P = one_rdm_from_G(self.G)
nav = particle_number(P)
print("# Initial walker energy: {} {} {}".format(*eloc))
print("# Initial walker electron number: {}".format(nav))
# self.buff_names = ['weight', 'G', 'unscaled_weight', 'phase', 'Tl',
# 'Ql', 'Dl', 'Tr', 'Qr', 'Dr', 'M0']
self.buff_names, self.buff_size = get_numeric_names(self.__dict__)
"sparse": False,
"integrals": "hamil.h5"
}
system = Generic(inputs=sys_opts)
# trial = OneBody(comm, system, 1.0, 0.05, verbose=True)
mus = numpy.arange(-1, 1)
data = []
dt = 0.05
fci = pd.read_csv('be_fixed_n.out', sep=r'\s+')
for b, n in zip(fci.beta, fci.N):
trial = OneBody(comm, system, b, dt, options={"nav": n}, verbose=True)
data.append([
local_energy(system, trial.P, opt=False)[0].real,
particle_number(trial.P).real
])
pl.plot(fci.beta, zip(*data)[0], label='Match N')
match = zip(*data)[0]
data = []
for b, n in zip(fci.beta, fci.N):
trial = MeanField(comm, system, b, dt, options={"nav": n}, verbose=True)
data.append([
local_energy(system, trial.P, opt=False)[0].real,
particle_number(trial.P).real
])
pl.plot(fci.beta, fci.E, label='FCI')
pl.plot(fci.beta, zip(*data)[0], label='THF', linestyle=':')
data = pd.DataFrame({
'beta': fci.beta,
'FCI': fci.E,
def delta_nav(dm, nav):
return particle_number(dm) - nav
def find_chemical_potential(system,
rho,
beta,
num_bins,
target,
deps=1e-6,
max_it=1000,
verbose=False):
# Todo: some sort of generic starting point independent of
# system/temperature
dmu1 = dmu2 = 1
mu1 = -1
mu2 = 1
sign = -1 if system._alt_convention else 1
if verbose:
print("# Finding chemical potential to match <N> = {:13.8e}".format(
target))
while numpy.sign(dmu1) * numpy.sign(dmu2) > 0:
rho1 = compute_rho(rho, mu1, beta, sign=sign)
dmat = one_rdm_stable(rho1, num_bins)
dmu1 = delta_nav(dmat, target)
rho2 = compute_rho(rho, mu2, beta, sign=sign)
dmat = one_rdm_stable(rho2, num_bins)
dmu2 = delta_nav(dmat, target)
if numpy.sign(dmu1) * numpy.sign(dmu2) < 0:
if verbose:
print("# Chemical potential lies within range of [%f,%f]" %
(mu1, mu2))
print("# delta_mu1 = %f, delta_mu2 = %f" %
(dmu1.real, dmu2.real))
break
else:
mu1 -= 2
mu2 += 2
if verbose:
print("# Increasing chemical potential search to [%f,%f]" %
(mu1, mu2))
found_mu = False
if verbose:
print("# " +
format_fixed_width_strings(['iteration', 'mu', 'Dmu', '<N>']))
for i in range(0, max_it):
mu = 0.5 * (mu1 + mu2)
rho_mu = compute_rho(rho, mu, beta, sign=sign)
dmat = one_rdm_stable(rho_mu, num_bins)
dmu = delta_nav(dmat, target).real
if verbose:
out = [i, mu, dmu, particle_number(dmat).real]
print("# " + format_fixed_width_floats(out))
if abs(dmu) < deps:
found_mu = True
break
else:
if dmu * dmu1 > 0:
mu1 = mu
elif dmu * dmu2 > 0:
mu2 = mu
if found_mu:
return mu
else:
print("# Error chemical potential not found")
return None
