[0.4.0] - 2019-04-28
Backwards incompatible changes
The argument order of
tenpy.models.lattice.Lattice
could be a tuple(priority, snake_winding)
before. This is no longer valid and needs to be replaced by("standard", snake_winding, priority)
.Moved the boundary conditions bc_coupling from the
tenpy.models.model.CouplingModel
into thetenpy.models.lattice.Lattice
(as bc). Using the parameter bc_coupling will raise a FutureWarning, one should set the boundary conditions directly in the lattice.Added parameter permute (True by default) in
tenpy.networks.mps.MPS.from_product_state()
andtenpy.networks.mps.MPS.from_Bflat()
. The resulting state will therefore be independent of the “conserve” parameter of the Sites - unlike before, where the meaning of the p_state argument might have changed.Generalize and rename
tenpy.networks.site.DoubleSite
totenpy.networks.site.GroupedSite
, to allow for an arbitrary number of sites to be grouped. Argumentssite0, site1, label0, label1
of the __init__ can be replaced with[site0, site1], [label0, label1]
andop0, op1
of the kronecker_product with[op0, op1]
; this will recover the functionality of the DoubleSite.Restructured callstructure of Mixer in DMRG, allowing an implementation of other mixers. To enable the mixer, set the DMRG parameter
"mixer"
toTrue
or'DensityMatrixMixer'
instead of just'Mixer'
.The interaction parameter in the
tenpy.models.bose_hubbbard_chain.BoseHubbardModel
(andtenpy.models.bose_hubbbard_chain.BoseHubbardChain
) did not correspond to \(U/2 N (N-1)\) as claimed in the Hamiltonian, but to \(U N^2\). The correcting factor 1/2 and change in the chemical potential have been fixed.Major restructuring of
tenpy.linalg.np_conserved
andtenpy.linalg.charges
. This should not break backwards-compatibility, but if you compiled the cython files, you need to remove the old binaries in the source directory. Usingbash cleanup.sh
might be helpful to do that, but also remove other files within the repository, so be careful and make a backup beforehand to be on the save side. Afterwards recompile withbash compile.sh
.Changed structure of
tenpy.models.model.CouplingModel.onsite_terms
andtenpy.models.model.CouplingModel.coupling_terms
: Each of them is now a dictionary with category strings as keys and the newly introducedtenpy.networks.terms.OnsiteTerms
andtenpy.networks.terms.CouplingTerms
as values.tenpy.models.model.CouplingModel.calc_H_onsite()
is deprecated in favor of new methods.Argument raise_op2_left of
tenpy.models.model.CouplingModel.add_coupling()
is deprecated.
Added
tenpy.networks.mps.MPS.canonical_form_infinite()
.tenpy.networks.mps.MPS.expectation_value_term()
,tenpy.networks.mps.MPS.expectation_value_terms_sum()
andtenpy.networks.mps.MPS.expectation_value_multi_sites()
for expectation values of terms.tenpy.networks.mpo.MPO.expectation_value()
for an MPO.tenpy.linalg.np_conserved.Array.extend()
andtenpy.linalg.charges.LegCharge.extend()
, allowing to extend an Array with zeros.DMRG parameter
'orthogonal_to'
allows to calculate excited states for finite systems.possibility to change the number of charges after creating LegCharges/Arrays.
more general way to specify the order of sites in a
tenpy.models.lattice.Lattice
.new
tenpy.models.lattice.Triangular
,tenpy.models.lattice.Honeycomb
andtenpy.models.lattice.Kagome
latticea way to specify nearest neighbor couplings in a
Lattice
, along with methods to count the number of nearest neighbors for sites in the bulk, and a way to plot them (plot_coupling()
and friends)tenpy.networks.mpo.MPO.from_grids()
to generate the MPO from a grid.tenpy.models.model.MultiCouplingModel
for couplings involving more than 2 sites.request #8: Allow shift in boundary conditions of
CouplingModel
.Allow to use state labels in
tenpy.networks.mps.MPS.from_product_state()
.tenpy.models.model.CouplingMPOModel
structuring the default initialization of most models.Allow to force periodic boundary conditions for finite MPS in the
CouplingMPOModel
. This is not recommended, though.tenpy.models.model.NearestNeighborModel.calc_H_MPO_from_bond()
andtenpy.models.model.MPOModel.calc_H_bond_from_MPO()
for conversion of H_bond into H_MPO and vice versa.tenpy.algorithms.tebd.RandomUnitaryEvolution
for random unitary circuitsAllow documentation links to github issues, arXiv, papers by doi and the forum with e.g.
:issue:`5`, :arxiv:`1805.00055`, :doi:`10.21468/SciPostPhysLectNotes.5`, :forum:`3`
tenpy.models.model.CouplingModel.coupling_strength_add_ext_flux()
for adding hoppings with external flux.tenpy.models.model.CouplingModel.plot_coupling_terms()
to visualize the added coupling terms.tenpy.networks.terms.OnsiteTerms
,tenpy.networks.terms.CouplingTerms
,tenpy.networks.terms.MultiCouplingTerm
containing the of terms for theCouplingModel
andMultiCouplingModel
. This allowed to add the category argument toadd_onsite
,add_coupling
andadd_multi_coupling
.tenpy.networks.terms.TermList
as another (more human readable) representation of terms with conversion from and to the other*Term
classes.tenpy.networks.mps.MPS.init_LP()
andtenpy.networks.mps.MPS.init_RP()
to initialize left and right parts of an Environment.tenpy.networks.mpo.MPOGraph.from_terms()
andtenpy.networks.mpo.MPOGraph.from_term_list()
.argument charge_sector in
tenpy.networks.mps.MPS.correlation_length()
.
Changed
moved toycodes from the folder
examples/
to a new foldertoycodes/
to separate them clearly.- major remodelling of the internals of
tenpy.linalg.np_conserved
andtenpy.linalg.charges
.
- major remodelling of the internals of
Restructured lanczos into a class, added time evolution calculating
exp(A*dt)|psi0>
Warning for poorly conditioned Lanczos; to overcome this enable the new parameter reortho.
Restructured
tenpy.algorithms.dmrg
:run()
is now just a wrapper around the newrun()
,run(psi, model, pars)
is roughly equivalent toeng = EngineCombine(psi, model, pars); eng.run()
.Added
init_env()
andreset_stats()
to allow a simple restart of DMRG with slightly different parameters, e.g. for tuning Hamiltonian parameters.Call
canonical_form()
for infinite systems if the final state is not in canonical form.
Changed default values for some parameters:
set
trunc_params['chi_max'] = 100
. Not setting a chi_max at all will lead to memory problems. DisableDMRG_params['chi_list'] = None
by default to avoid conflicting settings.reduce to
mixer_params['amplitude'] = 1.e-5
. A too strong mixer screws DMRG up pretty bad.increase
Lanczos_params['N_cache'] = N_max
(i.e., keep all states)set
DMRG_params['P_tol_to_trunc'] = 0.05
and provide reasonable …_min and …_max values.increased (default) DMRG accuracy by setting
DMRG_params['max_E_err'] = 1.e-8
andDMRG_params['max_S_err'] = 1.e-5
.don’t check the (absolute) energy for convergence in Lanczos.
set
DMRG_params['norm_tol'] = 1.e-5
to check whether the final state is in canonical form.
Verbosity of
get_parameter()
reduced: Print parameters only for verbosity >=1. and default values only for verbosity >= 2.Don’t print the energy during real-time TEBD evolution - it’s preserved up to truncation errors.
Renamed the SquareLattice class to
tenpy.models.lattice.Square
for better consistency.auto-determine whether Jordan-Wigner strings are necessary in
add_coupling()
.The way the labels of npc Arrays are stored internally changed to a simple list with None entries. There is a deprecated propery setter yielding a dictionary with the labels.
renamed first_LP and last_RP arguments of
MPSEnvironment
andMPOEnvironment
to init_LP and init_RP.Testing: insetad of the (outdated) nose, we now use pytest <https://pytest.org> for testing.
Fixed
issue #22: Serious bug in
tenpy.linalg.np_conserved.inner()
: ifdo_conj=True
is used with non-zeroqtotal
, it returned 0. instead of non-zero values.avoid error in
tenpy.networks.mps.MPS.apply_local_op()
Don’t carry around total charge when using DMRG with a mixer
Corrected couplings of the FermionicHubbardChain
issue #2: memory leak in cython parts when using intelpython/anaconda
issue #4: incompatible data types.
issue #6: the CouplingModel generated wrong Couplings in some cases
issue #19: Convergence of energy was slow for infinite systems with
N_sweeps_check=1
more reasonable traceback in case of wrong labels
wrong dtype of npc.Array when adding/subtracting/… arrays of different data types
could get wrong H_bond for completely decoupled chains.
SVD could return outer indices with different axes
tenpy.networks.mps.MPS.overlap()
works now for MPS with different total charge (e.g. afterpsi.apply_local_op(i, 'Sp')
).skip existing graph edges in MPOGraph.add() when building up terms without the strength part.
Removed
Attribute chinfo of
Lattice
.