Пример #1
0
def SIAM(U, e_f, V, D, beta, filename="qmc_results.h5"):
    # Create hybridization function
    Delta = V**2 * Flat(D)

    # Construct the impurity solver with the inverse temperature
    # and the structure of the Green's functions
    S = Solver(beta=beta, gf_struct={'up': [0], 'down': [0]}, n_l=50)

    # Initialize the non-interacting Green's function S.G0_iw
    for name, g0 in S.G0_iw:
        g0 << inverse(iOmega_n - e_f - Delta)

    # Run the solver. The results will be in S.G_tau, S.G_iw and S.G_l
    S.solve(
        h_int=U * n('up', 0) * n('down', 0),  # Local Hamiltonian
        n_cycles=2000000,  # Number of QMC cycles
        length_cycle=50,  # Length of one cycle
        n_warmup_cycles=20000,  # Warmup cycles
        measure_g_l=
        True,  # Measure G_l (representation of G in terms of Legendre polynomials)
        use_norm_as_weight=
        True,  # Necessary option for the measurement of the density matrix
        measure_density_matrix=True,  # Measure reduced impurity density matrix
        measure_pert_order=True)  # Measure histogram of k

    # Save the results in an HDF5 file (only on the master node)
    if mpi.is_master_node():
        with HDFArchive(filename, 'w') as Results:
            Results["G_tau"] = S.G_tau
            Results["G_iw"] = S.G_iw
            Results["G_l"] = S.G_l
            Results["rho"] = S.density_matrix
            Results["k_histogram"] = S.perturbation_order_total
            Results["average_sign"] = S.average_sign
Пример #2
0
def SIAM(U, e_f, V, D, beta, filename="qmc_results.h5"):
    Delta = V**2 * Flat(D)
    N_MC = 1e5
    l_max = 10
    independent_samples = 16
    for l in range(l_max + 1):
        for i in range(independent_samples):
            S = Solver(beta=beta, gf_struct={'up': [0], 'down': [0]})
            # Initialize the non-interacting Green's function S.G0_iw
            for name, g0 in S.G0_iw:
                g0 << inverse(iOmega_n - e_f - Delta)
            # Run the solver. The results will be in S.G_tau, S.G_iw and S.G_l
            S.solve(
                h_int=U * n('up', 0) * n('down', 0),  # Local Hamiltonian
                n_cycles=int(N_MC / 2**l),  # Number of QMC cycles
                length_cycle=2**l,  # Length of one cycle
                n_warmup_cycles=int(N_MC / 2**l / 100),  #  Warmup cycles
                measure_g_tau=False,  #  Don't measure G_tau
                measure_g_l=False,  #  Don't measure G_l
                perform_post_proc=False,  #  Don't measure G_iw
                use_norm_as_weight=
                True,  # Necessary option for the measurement of the density matrix
                measure_density_matrix=
                True,  # Measure reduced impurity density matrix
                random_seed=i * 8521 + l * 14187 +
                mpi.rank * 7472)  # Random seed, very important!
            # Save the results in an HDF5 file (only on the master node)
            if mpi.is_master_node():
                with HDFArchive(filename) as Results:
                    Results["rho_l{}_i{}".format(l, i)] = S.density_matrix
Пример #3
0
def DMFT(U, e_d, t, beta, filename="dmft_results.h5"):
    # Construct the CT-HYB-QMC solver
    S = Solver(beta=beta, gf_struct={'up': [0], 'down': [0]}, n_l=50)

    # Initialize Delta
    Delta = GfImFreq(beta=beta, indices=[0])
    Delta << t**2 * SemiCircular(half_bandwidth=2 * t)

    # Now do the DMFT loop
    n_iter = 8
    for iter in range(n_iter):

        # Compute new S.G0_iw
        for name, g0 in S.G0_iw:
            g0 << inverse(iOmega_n - e_d - Delta)
        # Run the solver
        S.solve(
            h_int=U * n('up', 0) * n('down', 0),  # Local Hamiltonian
            n_cycles=200000,  # Number of QMC cycles
            length_cycle=50,  # Length of a cycle
            n_warmup_cycles=2000,  # How many warmup cycles
            measure_g_l=True)
        # Compute new Delta with the self-consistency condition while imposing paramagnetism
        g_l = (S.G_l['up'] + S.G_l['down']) / 2.
        Delta.set_from_legendre(t**2 * g_l)

        # Intermediate saves
        if mpi.is_master_node():
            with HDFArchive(filename) as Results:
                Results["G_tau_iter{}".format(iter)] = S.G_tau
                Results["G_iw_iter{}".format(iter)] = S.G_iw
                Results["G_l_iter{}".format(iter)] = S.G_l
                Results["Sigma_iter{}".format(iter)] = S.Sigma_iw

    if mpi.is_master_node():
        with HDFArchive(filename) as Results:
            Results["G_tau"] = S.G_tau
            Results["G_iw"] = S.G_iw
            Results["G_l"] = S.G_l
            Results["Sigma"] = S.Sigma_iw
Пример #4
0
from pytriqs.gf import *
from pytriqs.operators import *
from pytriqs.archive import *
import pytriqs.utility.mpi as mpi
from pytriqs.applications.impurity_solvers.cthyb import Solver

# Set up a few parameters
U = 2.5
half_bandwidth = 1.0
chemical_potential = U / 2.0
beta = 100
n_loops = 5

# Construct the CTQMC solver
S = Solver(beta=beta, gf_struct=[['up', [0]], ['down', [0]]])

# Initalize the Green's function to a semi circular DOS
S.G_iw << SemiCircular(half_bandwidth)

# Now do the DMFT loop
for i_loop in range(n_loops):

    # Compute new S.G0_iw with the self-consistency condition while imposing paramagnetism
    g = 0.5 * (S.G_iw['up'] + S.G_iw['down'])
    for name, g0 in S.G0_iw:
        g0 << inverse(iOmega_n + chemical_potential -
                      (half_bandwidth / 2.0)**2 * g)

    # Run the solver
    S.solve(
        h_int=U * n('up', 0) * n('down', 0),  # Local Hamiltonian
Пример #5
0
if p.offdiag:  # off-diagonal solver, 1 block NBand x NBand
    gf_struct = {'0': p.bands_T}
else:  # diagonal solver, NBand blocks 1 x 1
    gf_struct = {}
    for band in p.bands_T:
        gf_struct[band] = [0]

if mpi.is_master_node() and p.NBins == 1:
    stars = '**********************************************************'
    PrintAndWrite(
        '\n' + stars + '\n* CT_HYB solver START, iteration ' + str(NLoop) +
        '.\n' + stars + '\n', logfname)

S = Solver(beta=p.beta,
           gf_struct=gf_struct,
           n_iw=p.NMats,
           n_l=p.NLeg,
           n_tau=p.NTau)

if p.offdiag:  # off-diagonal solver, 1 block NBand x NBand
    for block, gw0 in S.G0_iw:
        gw0 << GF
else:  # diagonal solver, NBand blocks 1 x 1
    for block, gw0 in S.G0_iw:
        gw0 << GF[block, block]

# reading the Coulomb matrix from file ####################
U_M = sp.loadtxt('Umm.dat')

# model Hamiltonian and other operators ###################
h_int = Operator()
import os
if not os.path.exists('results_two_bands'):
    os.makedirs('results_two_bands')

# Parameters of the model
t = 1.0
beta = 10.0
n_loops = 10
filling = 'half'  # or 'quarter'
n_orbitals = 2

# Construct the solver
S = Solver(beta=beta,
           gf_struct={
               'up-0': [0],
               'up-1': [0],
               'down-0': [0],
               'down-1': [0]
           })

for coeff in [0.0, 0.1, 0.2]:

    # Run for several values of U
    for U in np.arange(1.0, 13.0, 1.0):

        J = coeff * U

        # Expression of mu for half and quarter filling
        if filling == 'half':
            mu = 0.5 * U + 0.5 * (U - 2 * J) + 0.5 * (U - 3 * J)
        elif filling == 'quarter':
Пример #7
0
gf_struct = op.set_operator_structure(spin_names, orb_names, off_diag=off_diag)

# Construct the 4-index U matrix U_{ijkl}
# The spherically-symmetric U matrix is parametrised by the radial integrals
# F_0, F_2, F_4, which are related to U and J. We use the functions provided
# in the TRIQS library to construct this easily:
U_mat = op.U_matrix(l=l, U_int=U, J_hund=J, basis='spherical')

# Set the interacting part of the local Hamiltonian
# Here we use the full rotationally-invariant interaction parametrised
# by the 4-index tensor U_{ijkl}.
# The TRIQS library provides a function to build this Hamiltonian from the U tensor:
H = op.h_int_slater(spin_names, orb_names, U_mat, off_diag=off_diag)

# Construct the solver
S = Solver(beta=beta, gf_struct=gf_struct)

# Set the hybridization function and G0_iw for the Bethe lattice
delta_iw = GfImFreq(indices=[0], beta=beta)
delta_iw << (half_bandwidth / 2.0)**2 * SemiCircular(half_bandwidth)
for name, g0 in S.G0_iw:
    g0 << inverse(iOmega_n + mu - delta_iw)

# Now start the DMFT loops
for i_loop in range(n_loop):

    # Determine the new Weiss field G0_iw self-consistently
    if i_loop > 0:
        g_iw = GfImFreq(indices=[0], beta=beta)
        # Impose paramagnetism
        for name, g in S.G_tau:
Пример #8
0
from pytriqs.gf import *
from pytriqs.operators import *
from pytriqs.applications.impurity_solvers.cthyb import Solver
from pytriqs.archive import HDFArchive
import pytriqs.utility.mpi as mpi

# Parameters
D, V, U = 1.0, 0.2, 4.0
e_f, beta = -U/2.0, 50

# Construct the impurity solver with the inverse temperature
# and the structure of the Green's functions
S = Solver(beta = beta, gf_struct = [ ('up',[0]), ('down',[0]) ], n_l = 100)

# Initialize the non-interacting Green's function S.G0_iw
for name, g0 in S.G0_iw: g0 << inverse(iOmega_n - e_f - V**2 * Wilson(D))

# Run the solver. The results will be in S.G_tau, S.G_iw and S.G_l
S.solve(h_int = U * n('up',0) * n('down',0),     # Local Hamiltonian
        n_cycles  = 500000,                      # Number of QMC cycles
        length_cycle = 200,                      # Length of one cycle
        n_warmup_cycles = 10000,                 # Warmup cycles
        measure_G_l = True)                      # Measure G_l

# Save the results in an HDF5 file (only on the master node)
if mpi.is_master_node():
    with HDFArchive("aim_solution.h5",'w') as Results:
        Results["G_tau"] = S.G_tau
        Results["G_iw"] = S.G_iw
        Results["G_l"] = S.G_l
Пример #9
0
from itertools import product
import numpy as np

import os
if not os.path.exists('results_two_bands'):
    os.makedirs('results_two_bands')

# Parameters of the model
t = 1.0
beta = 10.0
n_loops = 10
filling = 'half' # or 'quarter'
n_orbitals = 2

# Construct the solver
S = Solver(beta = beta, gf_struct = {'up-0':[0], 'up-1':[0], 'down-0':[0], 'down-1':[0]})

for coeff in [0.0, 0.1, 0.2]:

    # Run for several values of U
    for U in np.arange(1.0, 13.0, 1.0):

        J = coeff * U

        # Expression of mu for half and quarter filling
        if filling == 'half':
            mu = 0.5*U + 0.5*(U-2*J) + 0.5*(U-3*J)
        elif filling == 'quarter':
            mu = -0.81 + (0.6899-1.1099*coeff)*U + (-0.02548+0.02709*coeff-0.1606*coeff**2)*U**2

        # Set the interacting Kanamori hamiltonian
Пример #10
0
gf_struct = op.set_operator_structure(spin_names,orb_names,off_diag=off_diag) 

# Construct the 4-index U matrix U_{ijkl}
# The spherically-symmetric U matrix is parametrised by the radial integrals
# F_0, F_2, F_4, which are related to U and J. We use the functions provided
# in the TRIQS library to construct this easily:
U_mat = op.U_matrix(l=l, U_int=U, J_hund=J, basis='spherical')

# Set the interacting part of the local Hamiltonian
# Here we use the full rotationally-invariant interaction parametrised 
# by the 4-index tensor U_{ijkl}.
# The TRIQS library provides a function to build this Hamiltonian from the U tensor:
H = op.h_int_slater(spin_names,orb_names,U_mat,off_diag=off_diag)

# Construct the solver
S = Solver(beta=beta, gf_struct=gf_struct)

# Set the hybridization function and G0_iw for the Bethe lattice
delta_iw = GfImFreq(indices=[0], beta=beta)
delta_iw << (half_bandwidth/2.0)**2 * SemiCircular(half_bandwidth)
for name, g0 in S.G0_iw: g0 << inverse(iOmega_n + mu - delta_iw)

# Now start the DMFT loops
for i_loop in range(n_loop):

  # Determine the new Weiss field G0_iw self-consistently
  if i_loop > 0: 
    g_iw = GfImFreq(indices=[0], beta=beta)
    # Impose paramagnetism
    for name, g in S.G_tau: g_iw << g_iw + (0.5/n_orbs)*Fourier(g)
    # Compute S.G0_iw with the self-consistency condition
Пример #11
0
from pytriqs.operators import *
from pytriqs.archive import *
from pytriqs.applications.impurity_solvers.cthyb import Solver
import numpy as np

import os
if not os.path.exists('results_one_band'):
    os.makedirs('results_one_band')

# Parameters of the model
t = 1.0
beta = 10.0
n_loops = 10

# Construct the impurity solver
S = Solver(beta = beta, gf_struct = {'up':[0], 'down':[0]})

# I run for several values of U
for U in np.arange(1.0, 13.0):
    print 'U =', U

    # This is a first guess for G
    S.G_iw << SemiCircular(2*t)

    # DMFT loop with self-consistency
    for i in range(n_loops):
    
        print "\n\nIteration = %i / %i" % (i+1, n_loops)
    
        # Symmetrize the Green's function and use self-consistency
        g = 0.5 * ( S.G_iw['up'] + S.G_iw['down'] )
Пример #12
0
from pytriqs.gf.local import *
from pytriqs.operators import *
from pytriqs.applications.impurity_solvers.cthyb import Solver

# Parameters
D = 1.0         # Half-bandwidth of the bath
V = 0.2         # Hybridisation amplitude
U = 4.0         # Coulomb interaction
e_f = -U/2      # Local energy level
h = 0.01        # External field
beta = 50       # Inverse temperature

# Construct the impurity solver with the inverse temperature
# and the structure of the Green's functions
S = Solver(beta = beta, gf_struct = {'up':[0], 'down':[0]})

# Initialize the non-interacting Green's function S.G0_iw
# External magnetic field introduces Zeeman energy splitting between
# different spin components
S.G0_iw['up']   << inverse(iOmega_n - e_f + h/2 - V**2 * Wilson(D))
S.G0_iw['down'] << inverse(iOmega_n - e_f - h/2 - V**2 * Wilson(D))

# Run the solver
S.solve(h_int = U * n('up',0) * n('down',0),     # Local Hamiltonian
        n_cycles  = 500000,                      # Number of QMC cycles
        length_cycle = 200,                      # Length of one cycle
        n_warmup_cycles = 10000,                 # Warmup cycles
        measure_density_matrix = True,           # Measure the reduced density matrix
        use_norm_as_weight = True)               # Required to measure the density matrix

# Extract accumulated density matrix
Пример #13
0
from pytriqs.gf.local import *
from pytriqs.operators import *
from pytriqs.applications.impurity_solvers.cthyb import Solver
from pytriqs.archive import HDFArchive
import pytriqs.utility.mpi as mpi

# Parameters
D, V, U = 1.0, 0.2, 4.0
e_f, beta = -U/2.0, 50

# Construct the impurity solver with the inverse temperature
# and the structure of the Green's functions
S = Solver(beta = beta, gf_struct = {'up':[0], 'down':[0]}, n_l = 100)

# Initialize the non-interacting Green's function S.G0_iw
for name, g0 in S.G0_iw: g0 << inverse(iOmega_n - e_f - V**2 * Wilson(D))

# Run the solver. The results will be in S.G_tau, S.G_iw and S.G_l
S.solve(h_int = U * n('up',0) * n('down',0),     # Local Hamiltonian
        n_cycles  = 500000,                      # Number of QMC cycles
        length_cycle = 200,                      # Length of one cycle
        n_warmup_cycles = 10000,                 # Warmup cycles
        measure_g_l = True)                      # Measure G_l

# Save the results in an HDF5 file (only on the master node)
if mpi.is_master_node():
    with HDFArchive("aim_solution.h5",'w') as Results:
        Results["G_tau"] = S.G_tau
        Results["G_iw"] = S.G_iw
        Results["G_l"] = S.G_l
Пример #14
0
from pytriqs.operators import *
from pytriqs.archive import *
from pytriqs.applications.impurity_solvers.cthyb import Solver
import numpy as np

import os
if not os.path.exists('results_one_band'):
    os.makedirs('results_one_band')

# Parameters of the model
t = 1.0
beta = 10.0
n_loops = 10

# Construct the impurity solver
S = Solver(beta=beta, gf_struct={'up': [0], 'down': [0]})

# I run for several values of U
for U in np.arange(1.0, 13.0):
    print 'U =', U

    # This is a first guess for G
    S.G_iw << SemiCircular(2 * t)

    # DMFT loop with self-consistency
    for i in range(n_loops):

        print "\n\nIteration = %i / %i" % (i + 1, n_loops)

        # Symmetrize the Green's function and use self-consistency
        g = 0.5 * (S.G_iw['up'] + S.G_iw['down'])
Пример #15
0
#GF = ReadGW(NLoop,p.NBand,p.NMats,p.beta,p.bands_T,FitMin,FitMax,mpi.rank,p.offdiag,logfname)
#GF = FitTailGreen(GF,p.NBand,FitMin,FitMax,6)
GF = ReadGW2(NLoop,p.NBand,p.NMats,p.beta,p.bands_T,FitMin,FitMax,p.NFit,mpi.rank,p.offdiag,1,logfname)

if p.offdiag: # off-diagonal solver, 1 block NBand x NBand
	gf_struct = { '0': p.bands_T }
else:       # diagonal solver, NBand blocks 1 x 1
	gf_struct = {}
	for band in p.bands_T: gf_struct[band] = [0]

if mpi.is_master_node() and p.NBins == 1:
	stars = '**********************************************************'
	PrintAndWrite('\n'+stars+'\n* CT_HYB solver START, iteration '+str(NLoop)+'.\n'+stars+'\n',logfname)

S = Solver(beta = p.beta, gf_struct = gf_struct, n_iw = p.NMats, n_l = p.NLeg, n_tau = p.NTau)

if p.offdiag: # off-diagonal solver, 1 block NBand x NBand
	for block, gw0 in S.G0_iw: gw0 << GF
else:       # diagonal solver, NBand blocks 1 x 1
	for block, gw0 in S.G0_iw: gw0 << GF[block,block]

# reading the Coulomb matrix from file ####################
U_M = sp.loadtxt('Umm.dat')

# model Hamiltonian and other operators ###################
h_int = Operator()
N_tot = Operator()

for b1 in range(p.NBand):
	N_tot = N_tot + n('0',p.bands_T[b1])
Пример #16
0
from pytriqs.gf.local import *
from pytriqs.operators import *
from pytriqs.archive import HDFArchive
from pytriqs.applications.impurity_solvers.cthyb import Solver
import pytriqs.utility.mpi as mpi

D, V, U = 1.0, 0.2, 4.0
e_f, beta = -U/2.0, 50

# Construct the impurity solver
S = Solver(beta = beta, gf_struct = {'up':[0],'down':[0]})

# Loop for two random generators
for random_name in ['mt11213b','lagged_fibonacci607']:

    for spin, g0 in S.G0_iw:
        g0 << inverse(iOmega_n - e_f - V**2 * Wilson(D))

    # Solve using random_name as a generator
    S.solve(h_int = U * n('up',0) * n('down',0),   # Local Hamiltonian
            n_cycles = 100000,                     # Number of QMC cycles
            length_cycle = 200,                    # Length of one cycle
            n_warmup_cycles = 10000,               # Number of warmup cycles
            random_name = random_name)             # Name of the random generator

    # Save the results in an hdf5 file (only on the master node)
    if mpi.is_master_node():
        with HDFArchive("random.h5") as Results:
            Results["G_iw%s"%(random_name)] = S.G_iw
# A mask giving the k points inside the central patch
in_central_patch = (np.abs(kx) < np.pi/np.sqrt(2)) & (np.abs(ky) < np.pi/np.sqrt(2))

# Find the partial densities of states associated to the patches
energies, epsilon, rho, delta = {},{}, {}, {}
energies['even'] = np.extract(in_central_patch, epsk)
energies['odd'] = np.extract(np.invert(in_central_patch), epsk)
for patch in ['even','odd']:
    h = np.histogram(energies[patch], bins=n_bins, normed=True)
    epsilon[patch] = 0.5 * (h[1][0:-1] + h[1][1:])
    rho[patch] = h[0]
    delta[patch] = h[1][1]-h[1][0]

# Construct the impurity solver
S = Solver(beta = beta,
           gf_struct = {'even-up':[0], 'odd-up':[0], 'even-down':[0], 'odd-down':[0]}, n_l = 100)

# The local lattice Green's function
G = S.G0_iw.copy()

# Rotation
cn, cn_dag, nn = {}, {}, {}
for spin in ['up','down']:
    cn['1-%s'%spin] = (c('even-%s'%spin,0) + c('odd-%s'%spin,0)) / np.sqrt(2)
    cn['2-%s'%spin] = (c('even-%s'%spin,0) - c('odd-%s'%spin,0)) / np.sqrt(2)
    nn['1-%s'%spin] = dagger(cn['1-%s'%spin]) * cn['1-%s'%spin]
    nn['2-%s'%spin] = dagger(cn['2-%s'%spin]) * cn['2-%s'%spin]

# Local Hamiltonian
h_loc = U * (nn['1-up'] * nn['1-down'] + nn['2-up'] * nn['2-down'])
Пример #18
0
from pytriqs.gf import *
from pytriqs.operators import *
from pytriqs.applications.impurity_solvers.cthyb import Solver

# Parameters
D = 1.0  # Half-bandwidth of the bath
V = 0.2  # Hybridisation amplitude
U = 4.0  # Coulomb interaction
e_f = -U / 2  # Local energy level
h = 0.01  # External field
beta = 50  # Inverse temperature

# Construct the impurity solver with the inverse temperature
# and the structure of the Green's functions
S = Solver(beta=beta, gf_struct=[('up', [0]), ('down', [0])])

# Initialize the non-interacting Green's function S.G0_iw
# External magnetic field introduces Zeeman energy splitting between
# different spin components
S.G0_iw['up'] << inverse(iOmega_n - e_f + h / 2 - V**2 * Wilson(D))
S.G0_iw['down'] << inverse(iOmega_n - e_f - h / 2 - V**2 * Wilson(D))

# Run the solver
S.solve(
    h_int=U * n('up', 0) * n('down', 0),  # Local Hamiltonian
    n_cycles=500000,  # Number of QMC cycles
    length_cycle=200,  # Length of one cycle
    n_warmup_cycles=10000,  # Warmup cycles
    measure_density_matrix=True,  # Measure the reduced density matrix
    use_norm_as_weight=True)  # Required to measure the density matrix
Пример #19
0
from pytriqs.gf.local import *
from pytriqs.operators import *
from pytriqs.archive import *
import pytriqs.utility.mpi as mpi
from pytriqs.applications.impurity_solvers.cthyb import Solver

# Set up a few parameters
U = 2.5
half_bandwidth = 1.0
chemical_potential = U/2.0
beta = 100
n_loops = 5

# Construct the CTQMC solver
S = Solver(beta = beta, gf_struct = {'up':[0], 'down':[0]})

# Initalize the Green's function to a semi circular DOS
S.G_iw << SemiCircular(half_bandwidth)

# Now do the DMFT loop
for i_loop in range(n_loops):

    # Compute new S.G0_iw with the self-consistency condition while imposing paramagnetism
    g = 0.5 * (S.G_iw['up'] + S.G_iw['down'])
    for name, g0 in S.G0_iw:
        g0 << inverse(iOmega_n + chemical_potential - (half_bandwidth/2.0)**2 * g)

    # Run the solver
    S.solve(h_int = U * n('up',0) * n('down',0),    # Local Hamiltonian
            n_cycles = 5000,                        # Number of QMC cycles
            length_cycle = 200,                     # Length of a cycle
Пример #20
0
    def __init__(self, seedname, params):
        """
        Initialize solver at each inequivalent correlation shell

        Parameters
        ----------
        seedname : string
            seedname
        params : dict
            Input parameters
        """
        self._params = copy.deepcopy(params)
        # Construct a SumKDFT object
        self.SK = SumkDFT(hdf_file=seedname + '.h5',
                          use_dft_blocks=False,
                          h_field=0.0)
        u_file = HDFArchive(seedname + '.h5', 'r')
        self.Umat = u_file["DCore"]["Umat"]

        # Construct an impurity solver
        beta = float(params['system']['beta'])
        n_iw = int(params['system']['n_iw'])  # Number of Matsubara frequencies
        n_tau = int(params['system']['n_tau'])  # Number of tau points
        self.solver_name = params['impurity_solver']['name']

        self._solver_params = create_solver_params(params['impurity_solver'])
        if 'verbosity' in self._solver_params.keys():
            if not mpi.is_master_node():
                del self._solver_params['verbosity']

        self.S = []
        for ish in range(self.SK.n_inequiv_shells):

            # Use GF structure determined by DFT blocks
            gf_struct = self.SK.gf_struct_solver[ish]

            if self.solver_name == "TRIQS/cthyb":
                from pytriqs.applications.impurity_solvers.cthyb import Solver
                if params['system']['n_l'] > 0:
                    self._solver_params['measure_g_l'] = True
                    self._solver_params['measure_g_tau'] = False
                    self.S.append(
                        Solver(beta=beta,
                               gf_struct=gf_struct,
                               n_iw=n_iw,
                               n_tau=n_tau,
                               n_l=params['system']['n_l']))
                else:
                    self.S.append(
                        Solver(beta=beta,
                               gf_struct=gf_struct,
                               n_iw=n_iw,
                               n_tau=n_tau))
            elif self.solver_name == "TRIQS/hubbard-I":
                n_orb = self.SK.corr_shells[
                    self.SK.inequiv_to_corr[ish]]['dim'] / (self.SK.SO + 1)

                from hubbard_solver_matrix import Solver
                self.S.append(
                    Solver(beta=beta,
                           norb=n_orb,
                           n_msb=n_iw,
                           use_spin_orbit=self.SK.SO))
            elif self.solver_name == "ALPS/cthyb":
                from pytriqs.applications.impurity_solvers.alps_cthyb import Solver
                if params['system']['n_l'] > 0:
                    self.S.append(
                        Solver(beta=beta,
                               gf_struct=gf_struct,
                               assume_real=False,
                               n_iw=n_iw,
                               n_tau=n_tau,
                               n_l=params['system']['n_l']))
                else:
                    self.S.append(
                        Solver(beta=beta,
                               gf_struct=gf_struct,
                               assume_real=False,
                               n_iw=n_iw,
                               n_tau=n_tau))
            else:
                raise RuntimeError("Unknown solver " + self.solver_name)